Publications
2026
Greule P; Huang W; Stark M; Au-Yeung K H; Schwenk J; Reina-Gálvez J; Sürgers C; Wernsdorfer W; Wolf C; Willke P
Exchange-mediated spin–electric control of single molecules on surfaces Journal Article
In: Nat. Phys., 2026, ISSN: 1745-2481.
@article{Greule2026,
title = {Exchange-mediated spin–electric control of single molecules on surfaces},
author = {Paul Greule and Wantong Huang and Máté Stark and Kwan Ho Au-Yeung and Johannes Schwenk and Jose Reina-Gálvez and Christoph Sürgers and Wolfgang Wernsdorfer and Christoph Wolf and Philip Willke},
doi = {10.1038/s41567-026-03353-w},
issn = {1745-2481},
year = {2026},
date = {2026-06-29},
urldate = {2026-06-29},
journal = {Nat. Phys.},
publisher = {Springer Science and Business Media LLC},
abstract = {<jats:title>Abstract</jats:title>
<jats:p>Individual magnetic molecules are promising building blocks for quantum technologies owing to their chemical tunability, nanoscale dimensions and ability to self-assemble into ordered arrays. However, exploiting their properties in quantum information processing requires precise local control of their spin. Here we demonstrate spin–electric coupling for two molecular spin systems—iron phthalocyanine (FePc) and Fe–FePc complexes—adsorbed on a surface. We use electron spin resonance combined with scanning tunnelling microscopy to locally address them and electrically tune them using an applied bias voltage. These measurements reveal a nonlinear voltage dependence of the resonance frequency, linked to the energetic position of the molecular orbitals. We attribute this effect to a transport-mediated exchange field from the magnetic tip, providing a large, highly localized and broadly applicable spin–electric coupling mechanism. Finally, we demonstrate that the spin–electric coupling enables all-electrical coherent spin control. In Rabi oscillation measurements of both single and coupled Fe–FePc complexes, we show that the spin dynamics can be tuned using the exchange field, demonstrating a pathway towards electrically controlled quantum operations.</jats:p>},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
<jats:title>Abstract</jats:title>
<jats:p>Individual magnetic molecules are promising building blocks for quantum technologies owing to their chemical tunability, nanoscale dimensions and ability to self-assemble into ordered arrays. However, exploiting their properties in quantum information processing requires precise local control of their spin. Here we demonstrate spin–electric coupling for two molecular spin systems—iron phthalocyanine (FePc) and Fe–FePc complexes—adsorbed on a surface. We use electron spin resonance combined with scanning tunnelling microscopy to locally address them and electrically tune them using an applied bias voltage. These measurements reveal a nonlinear voltage dependence of the resonance frequency, linked to the energetic position of the molecular orbitals. We attribute this effect to a transport-mediated exchange field from the magnetic tip, providing a large, highly localized and broadly applicable spin–electric coupling mechanism. Finally, we demonstrate that the spin–electric coupling enables all-electrical coherent spin control. In Rabi oscillation measurements of both single and coupled Fe–FePc complexes, we show that the spin dynamics can be tuned using the exchange field, demonstrating a pathway towards electrically controlled quantum operations.</jats:p>
<jats:p>Individual magnetic molecules are promising building blocks for quantum technologies owing to their chemical tunability, nanoscale dimensions and ability to self-assemble into ordered arrays. However, exploiting their properties in quantum information processing requires precise local control of their spin. Here we demonstrate spin–electric coupling for two molecular spin systems—iron phthalocyanine (FePc) and Fe–FePc complexes—adsorbed on a surface. We use electron spin resonance combined with scanning tunnelling microscopy to locally address them and electrically tune them using an applied bias voltage. These measurements reveal a nonlinear voltage dependence of the resonance frequency, linked to the energetic position of the molecular orbitals. We attribute this effect to a transport-mediated exchange field from the magnetic tip, providing a large, highly localized and broadly applicable spin–electric coupling mechanism. Finally, we demonstrate that the spin–electric coupling enables all-electrical coherent spin control. In Rabi oscillation measurements of both single and coupled Fe–FePc complexes, we show that the spin dynamics can be tuned using the exchange field, demonstrating a pathway towards electrically controlled quantum operations.</jats:p>
Lee M; Lee Y; Lee T; Jenkins A; Han M; Lee S; Park B; Heinrich A; Kim K; Jayich A C B; Lee D
Harnessing magnetic vortex oscillations for local microwave sources in qubit control Journal Article
In: Phys. Rev. Applied, vol. 25, no. 4, 2026, ISSN: 2331-7019.
@article{Lee2026,
title = {Harnessing magnetic vortex oscillations for local microwave sources in qubit control},
author = {Myeongwon Lee and Yuhan Lee and Taekhyeon Lee and Alec Jenkins and Min-Wook Han and Soogil Lee and Byong-Guk Park and Andreas Heinrich and Kab-Jin Kim and Ania C. Bleszynski Jayich and Donghun Lee},
doi = {10.1103/j6c4-fpxc},
issn = {2331-7019},
year = {2026},
date = {2026-04-30},
journal = {Phys. Rev. Applied},
volume = {25},
number = {4},
publisher = {American Physical Society (APS)},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Le H; Taherpour S; Janković D; Wolf C
Overcoming limitations on gate fidelity in noisy static exchange-coupled surface qubits Journal Article
In: npj Quantum Inf, vol. 12, no. 1, 2026, ISSN: 2056-6387.
@article{Le2026,
title = {Overcoming limitations on gate fidelity in noisy static exchange-coupled surface qubits},
author = {Hoang-Anh Le and Saba Taherpour and Denis Janković and Christoph Wolf},
doi = {10.1038/s41534-026-01214-1},
issn = {2056-6387},
year = {2026},
date = {2026-03-07},
urldate = {2026-03-07},
journal = {npj Quantum Inf},
volume = {12},
number = {1},
publisher = {Springer Science and Business Media LLC},
abstract = {<jats:title>Abstract</jats:title>
<jats:p>
Recent experiments demonstrated that the spin state of individual atoms on surfaces can be quantum-coherently controlled through all-electric electron spin resonance. By constructing interacting arrays of atoms, this results in an atomic-scale qubit platform. However, the static exchange coupling between qubits, limited lifetime, and polarization of the initial state impose significant limits on high-fidelity quantum control. We address this issue using open quantum systems simulation and quantum optimal control theory. We demonstrate the conditions under which high-fidelity operations (
<jats:inline-formula>
<jats:alternatives>
<jats:tex-math>$${mathcal{F}},gtrsim, 0.9$$</jats:tex-math>
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:mrow>
<mml:mi>F</mml:mi>
<mml:mspace/>
<mml:mo>≳</mml:mo>
<mml:mspace/>
<mml:mn>0.9</mml:mn>
</mml:mrow>
</mml:math>
</jats:alternatives>
</jats:inline-formula>
) are feasible in this qubit platform, and show how the Krotov method of quantum optimal control theory adapts to specific noise sources to outperform the conventional Rabi drivings. Finally, we re-examine the experimental setup used in the initial demonstration of this qubit platform and propose optimized experimental designs to maximize gate fidelity in this platform.
</jats:p>},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
<jats:title>Abstract</jats:title>
<jats:p>
Recent experiments demonstrated that the spin state of individual atoms on surfaces can be quantum-coherently controlled through all-electric electron spin resonance. By constructing interacting arrays of atoms, this results in an atomic-scale qubit platform. However, the static exchange coupling between qubits, limited lifetime, and polarization of the initial state impose significant limits on high-fidelity quantum control. We address this issue using open quantum systems simulation and quantum optimal control theory. We demonstrate the conditions under which high-fidelity operations (
<jats:inline-formula>
<jats:alternatives>
<jats:tex-math>$${mathcal{F}},gtrsim, 0.9$$</jats:tex-math>
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:mrow>
<mml:mi>F</mml:mi>
<mml:mspace/>
<mml:mo>≳</mml:mo>
<mml:mspace/>
<mml:mn>0.9</mml:mn>
</mml:mrow>
</mml:math>
</jats:alternatives>
</jats:inline-formula>
) are feasible in this qubit platform, and show how the Krotov method of quantum optimal control theory adapts to specific noise sources to outperform the conventional Rabi drivings. Finally, we re-examine the experimental setup used in the initial demonstration of this qubit platform and propose optimized experimental designs to maximize gate fidelity in this platform.
</jats:p>
<jats:p>
Recent experiments demonstrated that the spin state of individual atoms on surfaces can be quantum-coherently controlled through all-electric electron spin resonance. By constructing interacting arrays of atoms, this results in an atomic-scale qubit platform. However, the static exchange coupling between qubits, limited lifetime, and polarization of the initial state impose significant limits on high-fidelity quantum control. We address this issue using open quantum systems simulation and quantum optimal control theory. We demonstrate the conditions under which high-fidelity operations (
<jats:inline-formula>
<jats:alternatives>
<jats:tex-math>$${mathcal{F}},gtrsim, 0.9$$</jats:tex-math>
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:mrow>
<mml:mi>F</mml:mi>
<mml:mspace/>
<mml:mo>≳</mml:mo>
<mml:mspace/>
<mml:mn>0.9</mml:mn>
</mml:mrow>
</mml:math>
</jats:alternatives>
</jats:inline-formula>
) are feasible in this qubit platform, and show how the Krotov method of quantum optimal control theory adapts to specific noise sources to outperform the conventional Rabi drivings. Finally, we re-examine the experimental setup used in the initial demonstration of this qubit platform and propose optimized experimental designs to maximize gate fidelity in this platform.
</jats:p>
2025
Reina-Gálvez J; Nachtigall M; Lorente N; Martinek J; Wolf C
Contrasting exchange-field and spin-transfer torque driving mechanisms in all-electric electron spin resonance Journal Article
In: Phys. Rev. B, vol. 112, no. 24, 2025, ISSN: 2469-9969.
@article{Reina-Gálvez2025d,
title = {Contrasting exchange-field and spin-transfer torque driving mechanisms in all-electric electron spin resonance},
author = {Jose Reina-Gálvez and Matyas Nachtigall and Nicolás Lorente and Jan Martinek and Christoph Wolf},
doi = {10.1103/nzhr-syhs},
issn = {2469-9969},
year = {2025},
date = {2025-12-08},
journal = {Phys. Rev. B},
volume = {112},
number = {24},
publisher = {American Physical Society (APS)},
abstract = {<jats:p>Understanding the coherent properties of electron spins driven by electric fields is crucial for their potential application in quantum-coherent nanoscience. In this work, we address two distinct driving mechanisms in electric-field-driven electron spin resonance as implemented in scanning tunneling spectroscopy. We study the origin of the driving field using a single-orbital Anderson impurity, connected to polarized leads and biased by a voltage modulated on resonance with a spin transition. By mapping the quantum master equation into a system of equations for the impurity spin, we identify two distinct driving mechanisms. Below the charging thresholds of the impurity, electron spin resonance is dominated by a magnetically exchange-driven mechanism or field-like torque. Conversely, above the charging threshold spin-transfer torque caused by the spin-polarized current through the impurity drives the spin transition. Only the first mechanism enables coherent quantum spin control, while the second one leads to fast decoherence and spin accumulation towards a non-equilibrium steady state. The electron spin resonance signals and spin dynamics vary significantly depending on which driving mechanism dominates, highlighting the potential for optimizing quantum-coherent control in electrically driven quantum systems.</jats:p>},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
<jats:p>Understanding the coherent properties of electron spins driven by electric fields is crucial for their potential application in quantum-coherent nanoscience. In this work, we address two distinct driving mechanisms in electric-field-driven electron spin resonance as implemented in scanning tunneling spectroscopy. We study the origin of the driving field using a single-orbital Anderson impurity, connected to polarized leads and biased by a voltage modulated on resonance with a spin transition. By mapping the quantum master equation into a system of equations for the impurity spin, we identify two distinct driving mechanisms. Below the charging thresholds of the impurity, electron spin resonance is dominated by a magnetically exchange-driven mechanism or field-like torque. Conversely, above the charging threshold spin-transfer torque caused by the spin-polarized current through the impurity drives the spin transition. Only the first mechanism enables coherent quantum spin control, while the second one leads to fast decoherence and spin accumulation towards a non-equilibrium steady state. The electron spin resonance signals and spin dynamics vary significantly depending on which driving mechanism dominates, highlighting the potential for optimizing quantum-coherent control in electrically driven quantum systems.</jats:p>
Reina-Gálvez J; Le H; Bui H T; Phark S; Lorente N; Wolf C
Efficient driving of a spin qubit using single-atom magnets Journal Article
In: Phys. Rev. Research, vol. 7, no. 4, 2025, ISSN: 2643-1564.
@article{Reina-Gálvez2025b,
title = {Efficient driving of a spin qubit using single-atom magnets},
author = {Jose Reina-Gálvez and Hoang-Anh Le and Hong Thi Bui and Soo-hyon Phark and Nicolás Lorente and Christoph Wolf},
url = {https://doi.org/10.1103/qpz5-s6fw},
doi = {10.1103/qpz5-s6fw},
issn = {2643-1564},
year = {2025},
date = {2025-12-08},
urldate = {2025-12-08},
journal = {Phys. Rev. Research},
volume = {7},
number = {4},
publisher = {American Physical Society (APS)},
abstract = {<jats:p>The realization of electron-spin resonance at the single-atom level using scanning tunneling microscopy has opened avenues for coherent quantum sensing and quantum state manipulation at the ultimate size limit. This allows us to build many-body Hamiltonians and the study of their complex physical behavior. Recently, a qubit platform has emerged from this field, raising questions about the driving mechanism from single-atom magnets. In this work, we demonstrate how single-atom magnets can be used to drive a nearby single spin qubit efficiently. We show that the modulation of exchange coupling is the primary driving force, which successfully reproduces Rabi rates in the tens of MHz range, consistent with experimental data, while also addressing critical aspects related to the optimization of experimental parameters.</jats:p>},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
<jats:p>The realization of electron-spin resonance at the single-atom level using scanning tunneling microscopy has opened avenues for coherent quantum sensing and quantum state manipulation at the ultimate size limit. This allows us to build many-body Hamiltonians and the study of their complex physical behavior. Recently, a qubit platform has emerged from this field, raising questions about the driving mechanism from single-atom magnets. In this work, we demonstrate how single-atom magnets can be used to drive a nearby single spin qubit efficiently. We show that the modulation of exchange coupling is the primary driving force, which successfully reproduces Rabi rates in the tens of MHz range, consistent with experimental data, while also addressing critical aspects related to the optimization of experimental parameters.</jats:p>
Switzer E D; Reina-Gálvez J; Giedke G; Rahman T S; Wolf C; Choi D; Lorente N
Unraveling spin entanglement using quantum gates with scanning tunneling microscopy-driven electron spin resonance Journal Article
In: Nanoscale Adv., vol. 7, no. 24, pp. 8048–8057, 2025, ISSN: 2516-0230.
@article{Switzer2025,
title = {Unraveling spin entanglement using quantum gates with scanning tunneling microscopy-driven electron spin resonance},
author = {Eric D. Switzer and Jose Reina-Gálvez and Géza Giedke and Talat S. Rahman and Christoph Wolf and Deung-Jang Choi and Nicolás Lorente},
doi = {10.1039/d5na00421g},
issn = {2516-0230},
year = {2025},
date = {2025-12-02},
urldate = {2025-12-02},
journal = {Nanoscale Adv.},
volume = {7},
number = {24},
pages = {8048--8057},
publisher = {Royal Society of Chemistry (RSC)},
abstract = {<jats:p>Quantum entanglement is a fundamental resource for quantum information processing, using ESR with the STM it is possible to control it on the atomic scale.</jats:p>},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
<jats:p>Quantum entanglement is a fundamental resource for quantum information processing, using ESR with the STM it is possible to control it on the atomic scale.</jats:p>
Lee J; Kim G; Seok H; Han S; Shim H; Cha Y; Son S; Choi H; Grzeszczyk M; Bogucki A; Choi Y; Kim S; Lee H; Park C; Kim G; Hwang H; Kim H; Lee D; Son S; Back G; Shin H; Choi D; Ollier A; Kim Y; Fang L; Han G; Jung G; Lee Y; Kim H; Watanabe K; Taniguchi T; Bae S; Heinrich A; Jang W; Kim T
Monolithically-Integrated van der Waals Synaptic Memory via Bulk Nano-Crystallization Journal Article
In: Adv. Sci., no. e10961, 2025.
@article{Lee2025c,
title = {Monolithically-Integrated van der Waals Synaptic Memory via Bulk Nano-Crystallization},
author = {Jinhyoung Lee and Gunhyoung Kim and Hyunho Seok and Sujeong Han and Hyunwoo Shim and Yoonmi Cha and Sihoon Son and Hyunbin Choi and Magdalena Grzeszczyk and Aleksander Bogucki and Yunseok Choi and Seungil Kim and Hyeonjeong Lee and Chaerin Park and Geonwook Kim and Hosin Hwang and Hyunho Kim and Dongho Lee and Seowoo Son and Geumji Back and Hyelim Shin and Donghwan Choi and Alexina Ollier and Yeon-Ji Kim and Lei Fang and Gyuho Han and Goo-Eun Jung and Youngi Lee and Hyeong-U Kim and Kenji Watanabe and Takashi Taniguchi and Sanghoon Bae and Andreas Heinrich and Won-Jun Jang and Taesung Kim},
url = {https://advanced.onlinelibrary.wiley.com/doi/10.1002/advs.202510961},
doi = {10.1002/advs.202510961},
year = {2025},
date = {2025-08-26},
urldate = {2025-08-26},
journal = {Adv. Sci.},
number = {e10961},
abstract = {Owing to the evolution of data-driven technologies, including the large language models, generative artificial intelligence, autonomous driving, and the internet of things requires advanced memory technology. However, conventional memory device structures and fabrication process have significant limitations for high-density integration. Herein, this study reports the monolithically-integrated 1-selector and 1-resistive (1S1R) synaptic memory in van der Waals (vdW) heterostructure, which overcomes the conventional limitations of device integration technologies. Single-step direct synthesis of vdW heterostructure and its corresponding 1S1R cell is fabricated via plasma-enhanced lattice-distortion. Scanning-transmission electron microscopy, and X-ray photoelectron spectroscopy are correlatively applied to observe the effects of plasma-enhanced nano-crystallization of bulk vdW VSe2. Furthermore, bipolar resistive switching dynamics have been spatially resolved with conductive atomic force microscopy. Furthermore, the artificial vdW heterostructure exhibits the synaptic functionality with interfacial charge accumulation at the 2D/3D interface, enabling linear weight updates across multiple resistance states with minimal nonlinearity. In conclusion, it envision that the monolithically-integrated 1S1R cell can offers a systematic device platform for next-generation vdW electronics and its corresponding monolithic 3D integration.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Owing to the evolution of data-driven technologies, including the large language models, generative artificial intelligence, autonomous driving, and the internet of things requires advanced memory technology. However, conventional memory device structures and fabrication process have significant limitations for high-density integration. Herein, this study reports the monolithically-integrated 1-selector and 1-resistive (1S1R) synaptic memory in van der Waals (vdW) heterostructure, which overcomes the conventional limitations of device integration technologies. Single-step direct synthesis of vdW heterostructure and its corresponding 1S1R cell is fabricated via plasma-enhanced lattice-distortion. Scanning-transmission electron microscopy, and X-ray photoelectron spectroscopy are correlatively applied to observe the effects of plasma-enhanced nano-crystallization of bulk vdW VSe2. Furthermore, bipolar resistive switching dynamics have been spatially resolved with conductive atomic force microscopy. Furthermore, the artificial vdW heterostructure exhibits the synaptic functionality with interfacial charge accumulation at the 2D/3D interface, enabling linear weight updates across multiple resistance states with minimal nonlinearity. In conclusion, it envision that the monolithically-integrated 1S1R cell can offers a systematic device platform for next-generation vdW electronics and its corresponding monolithic 3D integration.
Choi D; Phark S; Heinrich A J; Lorente N
Electron spin resonance with scanning tunneling microscopy: a tool for an on-surface quantum platform of identical qubits Journal Article
In: Nanoscale Adv., vol. 7, no. 15, pp. 4551–4558, 2025, ISSN: 2516-0230.
@article{Choi2025c,
title = {Electron spin resonance with scanning tunneling microscopy: a tool for an on-surface quantum platform of identical qubits},
author = {Deung-Jang Choi and Soo-hyon Phark and Andreas J. Heinrich and Nicolás Lorente},
doi = {10.1039/d5na00316d},
issn = {2516-0230},
year = {2025},
date = {2025-07-22},
urldate = {2025-07-22},
journal = {Nanoscale Adv.},
volume = {7},
number = {15},
pages = {4551--4558},
publisher = {Royal Society of Chemistry (RSC)},
abstract = {<jats:p>An on-surface quantum platform of identical spin qubits, made of three titanium atoms on an ultrathin magnesium oxide layer with atomic scale precision.</jats:p>},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
<jats:p>An on-surface quantum platform of identical spin qubits, made of three titanium atoms on an ultrathin magnesium oxide layer with atomic scale precision.</jats:p>
Choi D; Phark S; Heinrich A J; Lorente N
Electron spin resonance with scanning tunneling microscopy: a tool for an on-surface quantum platform of identical qubits Journal Article
In: Nanoscale Adv., vol. 7, no. 15, pp. 4551–4558, 2025, ISSN: 2516-0230.
@article{Choi2025b,
title = {Electron spin resonance with scanning tunneling microscopy: a tool for an on-surface quantum platform of identical qubits},
author = {Deung-Jang Choi and Soo-hyon Phark and Andreas J. Heinrich and Nicolás Lorente},
doi = {10.1039/d5na00316d},
issn = {2516-0230},
year = {2025},
date = {2025-07-22},
urldate = {2025-07-22},
journal = {Nanoscale Adv.},
volume = {7},
number = {15},
pages = {4551--4558},
publisher = {Royal Society of Chemistry (RSC)},
abstract = {An on-surface quantum platform of identical spin qubits, made of three titanium atoms on an ultrathin magnesium oxide layer with atomic scale precision.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
An on-surface quantum platform of identical spin qubits, made of three titanium atoms on an ultrathin magnesium oxide layer with atomic scale precision.
Choi ; Deung-Jang ; Phark ; Soo-hyon ; Heinrich ; J. A; Lorente ; Nicolás
Electron spin resonance with scanning tunneling microscopy: a tool for an on-surface quantum platform of identical qubits Journal Article
In: Nanoscale Adv., vol. 7, iss. 15, pp. 4551-4558, 2025.
@article{Choi2025,
title = {Electron spin resonance with scanning tunneling microscopy: a tool for an on-surface quantum platform of identical qubits },
author = {Choi and Deung-Jang and Phark and Soo-hyon and Heinrich and Andreas J. and Lorente and Nicolás},
url = {http://dx.doi.org/10.1039/D5NA00316D},
doi = {10.1039/D5NA00316D},
year = {2025},
date = {2025-07-10},
urldate = {2025-07-10},
journal = {Nanoscale Adv.},
volume = {7},
issue = {15},
pages = {4551-4558},
abstract = {Integration of electron spin resonance (ESR) in a scanning tunneling microscope (STM) has enabled all-electrical control of atomic and molecular spins on solid surfaces with atomic-scale precision and energy resolution beyond thermal limitations. Further, coherent manipulation and detection of individual spins in an ESR-STM establishes a powerful quantum platform, allowing for the implementation of fundamental quantum logic operations to on-surface identical qubits (same chemical species but ESR-adressable). In this review, we introduce recent advances of ESR-STM, focusing on its application to atomic-scale qubits and extension to molecular qubit systems. We discuss the principles underlying ESR-STM, followed by single-spin addressability, coherent control via Rabi oscillations, and quantum state readout through frequency-resolved detection. We further demonstrate multi-qubit control architectures enabled by atom manipulation and local magnetic field engineering, culminating in the realization of multi-qubit logic gates such as the Controlled-NOT and Toffoli gates. These implementations highlight the specialty of ESR-STM towards atomic-scale quantum circuits. Indeed, ESR-STM can be an excellent tool to perform and evaluate quantum operations in molecular qubits. The results reviewed in this collection establish ESR-STM as a versatile tool for advancing quantum coherent science at the atomic and molecular level in solid-state environments.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Integration of electron spin resonance (ESR) in a scanning tunneling microscope (STM) has enabled all-electrical control of atomic and molecular spins on solid surfaces with atomic-scale precision and energy resolution beyond thermal limitations. Further, coherent manipulation and detection of individual spins in an ESR-STM establishes a powerful quantum platform, allowing for the implementation of fundamental quantum logic operations to on-surface identical qubits (same chemical species but ESR-adressable). In this review, we introduce recent advances of ESR-STM, focusing on its application to atomic-scale qubits and extension to molecular qubit systems. We discuss the principles underlying ESR-STM, followed by single-spin addressability, coherent control via Rabi oscillations, and quantum state readout through frequency-resolved detection. We further demonstrate multi-qubit control architectures enabled by atom manipulation and local magnetic field engineering, culminating in the realization of multi-qubit logic gates such as the Controlled-NOT and Toffoli gates. These implementations highlight the specialty of ESR-STM towards atomic-scale quantum circuits. Indeed, ESR-STM can be an excellent tool to perform and evaluate quantum operations in molecular qubits. The results reviewed in this collection establish ESR-STM as a versatile tool for advancing quantum coherent science at the atomic and molecular level in solid-state environments.
Bogucki A; Łopion A; Połczyńska K E; Pacuski W; Kazimierczuk T; Golnik A; Kossacki P
In: Phys. Rev. B, vol. 112, iss. 3, no. 8, pp. 035407, 2025.
@article{Bogucki2025,
title = {Strain-induced speed-up of Mn2+ spin-lattice relaxation in (Cd,Mn)Te/(Cd,Mg)Te quantum wells: A time-resolved optically detected magnetic resonance study},
author = {A. Bogucki and A. Łopion and K. E. Połczyńska and W. Pacuski and T. Kazimierczuk and A. Golnik and P. Kossacki},
url = {https://link.aps.org/doi/10.1103/q3jm-k7z3},
doi = {10.1103/q3jm-k7z3},
year = {2025},
date = {2025-07-07},
urldate = {2025-07-07},
journal = {Phys. Rev. B},
volume = {112},
number = {8},
issue = {3},
pages = {035407},
abstract = {This study examines the spin-lattice relaxation rate of Mn2+ ions in strained diluted magnetic semiconductor (Cd,Mn)Te/(Cd,Mg)Te quantum wells using the optically detected magnetic resonance (ODMR) technique. By adjusting the magnesium (Mg) content in the buffer layer, we created samples with different strain levels. Our time-resolved ODMR results show that the spin-lattice relaxation time becomes faster as strain increases. We also found that the relaxation rate increases with both magnetic field and temperature, showing a power-law behavior. To understand these observations, we used a theoretical model based on six-level rate equations with nonequal level separations. This model suggests that the main factor affecting relaxation in our samples is a “direct” mechanism. The model's predictions match well with our experimental data. Overall, our findings give insights into spin-lattice relaxation in strained quantum wells and could be important for the development of future quantum and spintronic devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
This study examines the spin-lattice relaxation rate of Mn2+ ions in strained diluted magnetic semiconductor (Cd,Mn)Te/(Cd,Mg)Te quantum wells using the optically detected magnetic resonance (ODMR) technique. By adjusting the magnesium (Mg) content in the buffer layer, we created samples with different strain levels. Our time-resolved ODMR results show that the spin-lattice relaxation time becomes faster as strain increases. We also found that the relaxation rate increases with both magnetic field and temperature, showing a power-law behavior. To understand these observations, we used a theoretical model based on six-level rate equations with nonequal level separations. This model suggests that the main factor affecting relaxation in our samples is a “direct” mechanism. The model's predictions match well with our experimental data. Overall, our findings give insights into spin-lattice relaxation in strained quantum wells and could be important for the development of future quantum and spintronic devices.
Bogucki A; Łopion A; Połczyńska K E; Pacuski W; Kazimierczuk T; Golnik A; Kossacki P
In: Phys. Rev. B, vol. 112, no. 3, 2025, ISSN: 2469-9969.
@article{Bogucki2025b,
title = {Strain-induced speed-up of Mn2+ spin-lattice relaxation in (Cd,Mn)Te/(Cd,Mg)Te quantum wells: A time-resolved optically detected magnetic resonance study},
author = {A. Bogucki and A. Łopion and K. E. Połczyńska and W. Pacuski and T. Kazimierczuk and A. Golnik and P. Kossacki},
doi = {10.1103/q3jm-k7z3},
issn = {2469-9969},
year = {2025},
date = {2025-07-07},
journal = {Phys. Rev. B},
volume = {112},
number = {3},
publisher = {American Physical Society (APS)},
abstract = {<jats:p>This study examines the spin-lattice relaxation rate of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:msup><a:mrow><a:mi>Mn</a:mi></a:mrow><a:mrow><a:mn>2</a:mn><a:mo>+</a:mo></a:mrow></a:msup></a:math> ions in strained diluted magnetic semiconductor (Cd,Mn)Te/(Cd,Mg)Te quantum wells using the optically detected magnetic resonance (ODMR) technique. By adjusting the magnesium (Mg) content in the buffer layer, we created samples with different strain levels. Our time-resolved ODMR results show that the spin-lattice relaxation time becomes faster as strain increases. We also found that the relaxation rate increases with both magnetic field and temperature, showing a power-law behavior. To understand these observations, we used a theoretical model based on six-level rate equations with nonequal level separations. This model suggests that the main factor affecting relaxation in our samples is a “direct” mechanism. The model's predictions match well with our experimental data. Overall, our findings give insights into spin-lattice relaxation in strained quantum wells and could be important for the development of future quantum and spintronic devices.</jats:p>},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
<jats:p>This study examines the spin-lattice relaxation rate of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:msup><a:mrow><a:mi>Mn</a:mi></a:mrow><a:mrow><a:mn>2</a:mn><a:mo>+</a:mo></a:mrow></a:msup></a:math> ions in strained diluted magnetic semiconductor (Cd,Mn)Te/(Cd,Mg)Te quantum wells using the optically detected magnetic resonance (ODMR) technique. By adjusting the magnesium (Mg) content in the buffer layer, we created samples with different strain levels. Our time-resolved ODMR results show that the spin-lattice relaxation time becomes faster as strain increases. We also found that the relaxation rate increases with both magnetic field and temperature, showing a power-law behavior. To understand these observations, we used a theoretical model based on six-level rate equations with nonequal level separations. This model suggests that the main factor affecting relaxation in our samples is a “direct” mechanism. The model's predictions match well with our experimental data. Overall, our findings give insights into spin-lattice relaxation in strained quantum wells and could be important for the development of future quantum and spintronic devices.</jats:p>
Phark S; Weber B; Yoshida Y; Forrester P R; Elbertse R J G; Stroscio J A; Wang H; Yang K; Gross L; Mishra S; Paschke F; Kaiser K; Fatayer S; Repp J; Anderson H; Peña D; Albrecht F; Giessibl F J; Fasel R; Fernández-Rossier J; Kawai S; Limot L; Lorente N; Jaeck B; Huang H; Ankerhold J; Ast C R; Trahms M; Winkelmann C; Franke K J; Soldini M; Wagner G; Neupert T; Küster F; Das S; Parkin S; Sessi P; Wang Z; Madhavan V; Huber R; Singh G; Donati F; Rusponi S; Brune H; Moreno-Pineda E; Ruben M; Wernsdorfer W; Huang W; Au-Yeung K H; Willke P; Heinrich A J; Baumann S; Loth S; Veldman L M; Otte S; Wolf C; Sellies L; Schofield S R; Flatte M E; Keizer J G; Simmons M Y
Roadmap on Atomically-Engineered Quantum Platforms Journal Article
In: Nano Futures, 2025.
@article{Phark2025,
title = {Roadmap on Atomically-Engineered Quantum Platforms},
author = {Soo-hyon Phark and Bent Weber and Yasuo Yoshida and Patrick Robert Forrester and Robertus Johannes Gerardus Elbertse and Joseph A Stroscio and Hao Wang and Kai Yang and Leo Gross and Shantanu Mishra and Fabian Paschke and Katharina Kaiser and Shadi Fatayer and Jascha Repp and Harry Anderson and Diego Peña and Florian Albrecht and Franz Josef Giessibl and Roman Fasel and Joaquín Fernández-Rossier and Shigeki Kawai and Laurence Limot and Nicolas Lorente and Berthold Jaeck and Haonan Huang and Joachim Ankerhold and Christian R. Ast and Martina Trahms and Clemens Winkelmann and Katharina Jennifer Franke and Martina Soldini and Glenn Wagner and Titus Neupert and Felix Küster and Souvik Das and Stuart Parkin and Paolo Sessi and Zhenyu Wang and Vidya Madhavan and Rupert Huber and Gagandeep Singh and Fabio Donati and Stefano Rusponi and Harald Brune and Eufemio Moreno-Pineda and Mario Ruben and Wolfgang Wernsdorfer and Wantong Huang and Kwan Ho Au-Yeung and Philip Willke and Andreas J. Heinrich and Susanne Baumann and Sebastian Loth and Lukas Maarten Veldman and Sander Otte and Christoph Wolf and Lisanne Sellies and Steven R Schofield and Michael E Flatte and Joris G Keizer and Michelle Y Simmons},
url = {https://iopscience.iop.org/article/10.1088/2399-1984/ade6b7/meta},
doi = {10.1088/2399-1984/ade6b7},
year = {2025},
date = {2025-06-20},
urldate = {2025-06-20},
journal = {Nano Futures},
abstract = {Matter at the atomic-scale is inherently governed by the laws of quantum mechanics. This makes charges and spins confined to individual atoms – and interactions among them – an invaluable resource for fundamental research and quantum technologies alike. However, harnessing the inherent “quantumness” of atomic-scale objects requires that they can be precisely engineered and addressed at the individual atomic level. Since its invention in the 1980s, scanning tunneling microscopy (STM) has repeatedly demonstrated the unrivalled ability to not only resolve but manipulate matter at atomic length scales. Over the past decades, this has enabled the design and investigation of bottom-up tailored nanostructures as reliable and reproducible platforms to study designer quantum physics and chemistry, band topology, and collective phenomena. The vast range of STM-based techniques and modes of operation, as well as their combination with electromagnetic fields from the infrared to microwave spectral range, has even allowed for the precise control of individual charge and spin degrees of freedom. This roadmap reviews the most recent developments in the field of atomically-engineered quantum platforms and explores their potential in future fundamental research and quantum technologies.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Matter at the atomic-scale is inherently governed by the laws of quantum mechanics. This makes charges and spins confined to individual atoms – and interactions among them – an invaluable resource for fundamental research and quantum technologies alike. However, harnessing the inherent “quantumness” of atomic-scale objects requires that they can be precisely engineered and addressed at the individual atomic level. Since its invention in the 1980s, scanning tunneling microscopy (STM) has repeatedly demonstrated the unrivalled ability to not only resolve but manipulate matter at atomic length scales. Over the past decades, this has enabled the design and investigation of bottom-up tailored nanostructures as reliable and reproducible platforms to study designer quantum physics and chemistry, band topology, and collective phenomena. The vast range of STM-based techniques and modes of operation, as well as their combination with electromagnetic fields from the infrared to microwave spectral range, has even allowed for the precise control of individual charge and spin degrees of freedom. This roadmap reviews the most recent developments in the field of atomically-engineered quantum platforms and explores their potential in future fundamental research and quantum technologies.
Huang W; Stark M; Greule P; Au-Yeung K H; Sostina D; Gálvez J R; Sürgers C; Wernsdorfer W; Wolf C; Willke P
Quantum spin-engineering in on-surface molecular ferrimagnets Journal Article
In: Nat Commun, vol. 16, no. 1, 2025, ISSN: 2041-1723.
@article{Huang2025b,
title = {Quantum spin-engineering in on-surface molecular ferrimagnets},
author = {Wantong Huang and Máté Stark and Paul Greule and Kwan Ho Au-Yeung and Daria Sostina and José Reina Gálvez and Christoph Sürgers and Wolfgang Wernsdorfer and Christoph Wolf and Philip Willke},
doi = {10.1038/s41467-025-60409-w},
issn = {2041-1723},
year = {2025},
date = {2025-06-05},
journal = {Nat Commun},
volume = {16},
number = {1},
publisher = {Springer Science and Business Media LLC},
abstract = {<jats:title>Abstract</jats:title>
<jats:p>
The design and control of atomic-scale spin structures constitute major challenges for spin-based quantum technology platforms, including quantum dots, color centers, and molecular spins. Here, we showcase a strategy for designing the quantum properties of molecular spin qubits by combining tip-assisted on-surface assembly with electron spin resonance scanning tunneling microscopy (ESR-STM): We fabricate magnetic dimer complexes that consist of an iron phthalocyanine (FePc) molecule and an organometallic half-sandwich complex formed by the FePc ligand and an attached iron atom, Fe(C
<jats:sub>6</jats:sub>
H
<jats:sub>6</jats:sub>
). The total complex forms a mixed-spin (1/2,1) quantum ferrimagnet with a well-separated correlated ground state doublet, which we utilize for coherent control. As a result of the correlation, the quantum ferrimagnet shows an improved spin lifetime ( > 1.5 μs) as it is partially protected against inelastic electron scattering. Lastly, the ferrimagnet units also enable intermolecular coupling, that can be used to realize both ferromagnetic or antiferromagnetic structures. Thus, quantum ferrimagnets provide a versatile platform to improve coherent control in general and to study complex magnetic interactions.
</jats:p>},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
<jats:title>Abstract</jats:title>
<jats:p>
The design and control of atomic-scale spin structures constitute major challenges for spin-based quantum technology platforms, including quantum dots, color centers, and molecular spins. Here, we showcase a strategy for designing the quantum properties of molecular spin qubits by combining tip-assisted on-surface assembly with electron spin resonance scanning tunneling microscopy (ESR-STM): We fabricate magnetic dimer complexes that consist of an iron phthalocyanine (FePc) molecule and an organometallic half-sandwich complex formed by the FePc ligand and an attached iron atom, Fe(C
<jats:sub>6</jats:sub>
H
<jats:sub>6</jats:sub>
). The total complex forms a mixed-spin (1/2,1) quantum ferrimagnet with a well-separated correlated ground state doublet, which we utilize for coherent control. As a result of the correlation, the quantum ferrimagnet shows an improved spin lifetime ( > 1.5 μs) as it is partially protected against inelastic electron scattering. Lastly, the ferrimagnet units also enable intermolecular coupling, that can be used to realize both ferromagnetic or antiferromagnetic structures. Thus, quantum ferrimagnets provide a versatile platform to improve coherent control in general and to study complex magnetic interactions.
</jats:p>
<jats:p>
The design and control of atomic-scale spin structures constitute major challenges for spin-based quantum technology platforms, including quantum dots, color centers, and molecular spins. Here, we showcase a strategy for designing the quantum properties of molecular spin qubits by combining tip-assisted on-surface assembly with electron spin resonance scanning tunneling microscopy (ESR-STM): We fabricate magnetic dimer complexes that consist of an iron phthalocyanine (FePc) molecule and an organometallic half-sandwich complex formed by the FePc ligand and an attached iron atom, Fe(C
<jats:sub>6</jats:sub>
H
<jats:sub>6</jats:sub>
). The total complex forms a mixed-spin (1/2,1) quantum ferrimagnet with a well-separated correlated ground state doublet, which we utilize for coherent control. As a result of the correlation, the quantum ferrimagnet shows an improved spin lifetime ( > 1.5 μs) as it is partially protected against inelastic electron scattering. Lastly, the ferrimagnet units also enable intermolecular coupling, that can be used to realize both ferromagnetic or antiferromagnetic structures. Thus, quantum ferrimagnets provide a versatile platform to improve coherent control in general and to study complex magnetic interactions.
</jats:p>
Lee J; Kim G; Seok H; Choi H; Lee H; Lee S; Kim G; Kim H; Son S; Son S; Lee D; Hwang H; Shin H; Han S; Back G; Ollier A; Kim Y; Fang L; Han G; Jung G; Lee Y; Kim H; Watanabe K; Taniguchi T; Shin W; Cheema S; Heinrich A; Jang W; Kim T
Artificial Room-Temperature Ferromagnetism of Bulk van der Waals VSe2 Journal Article
In: Adv. Sci., vol. 12, iss. 34, no. e04746, 2025, ISSN: 2198-3844.
@article{Lee2025,
title = {Artificial Room-Temperature Ferromagnetism of Bulk van der Waals VSe2},
author = {Jinhyoung Lee and Gunhyoung Kim and Hyunho Seok and Hyunbin Choi and Hyeonjeong Lee and Seokchan Lee and Geonwook Kim and Hyunho Kim and Seowoo Son and Sihoon Son and Dongho Lee and Hosin Hwang and Hyelim Shin and Sujeong Han and Geumji Back and Alexina Ollier and Yeon-Ji Kim and Lei Fang and Gyuho Han and Goo-Eun Jung and Youngi Lee and Hyeong-U Kim and Kenji Watanabe and Takashi Taniguchi and Wonjun Shin and Suraj Cheema and Andreas Heinrich and Won-Jun Jang and Taesung Kim},
url = {https://advanced.onlinelibrary.wiley.com/doi/full/10.1002/advs.202504746},
doi = {10.1002/advs.202504746},
issn = {2198-3844},
year = {2025},
date = {2025-05-30},
urldate = {2025-05-30},
journal = {Adv. Sci.},
volume = {12},
number = {e04746},
issue = {34},
abstract = {Originating from spin and orbital motion, van der Waals (vdW) ferromagnetism has emerged as a significant platform to experimentally access the fundamental physics of magnetism in reduced dimensions, including quantum computing, sensing, and data storage. However, currently, available vdW ferromagnetic materials can be achieved with mechanical exfoliation and low-temperature operation, which completely limits the monolithic integration of vdW ferromagnets with other functional materials. Nonetheless, the direct synthesis of room-temperature vdW ferromagnets has not been achieved commercially, owing to the imprecise control of the layer-by-layer growth, high-temperature synthesis, and low yield. To overcome these limitations, herein, an artificial vdW ferromagnetic platform has been reported, which activates the nano-crystallization and its corresponding ferromagnetism in bulk VSe2 via Ar + H2S plasma sulfurization. Sweeping the magnetic field, vdW ferromagnetism has been spatially resolved, which experimentally correlates with magnetization reversal behavior and domain pinning effects. Furthermore, nano-crystallization of VSe2 is clearly validated with transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and selected area diffraction analysis. In conclusion, it is envisioned that the artificial vdW ferromagnetic platform can artificially inject the ferromagnetism in bulk vdW VSe2, which has not been possible previously.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Originating from spin and orbital motion, van der Waals (vdW) ferromagnetism has emerged as a significant platform to experimentally access the fundamental physics of magnetism in reduced dimensions, including quantum computing, sensing, and data storage. However, currently, available vdW ferromagnetic materials can be achieved with mechanical exfoliation and low-temperature operation, which completely limits the monolithic integration of vdW ferromagnets with other functional materials. Nonetheless, the direct synthesis of room-temperature vdW ferromagnets has not been achieved commercially, owing to the imprecise control of the layer-by-layer growth, high-temperature synthesis, and low yield. To overcome these limitations, herein, an artificial vdW ferromagnetic platform has been reported, which activates the nano-crystallization and its corresponding ferromagnetism in bulk VSe2 via Ar + H2S plasma sulfurization. Sweeping the magnetic field, vdW ferromagnetism has been spatially resolved, which experimentally correlates with magnetization reversal behavior and domain pinning effects. Furthermore, nano-crystallization of VSe2 is clearly validated with transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and selected area diffraction analysis. In conclusion, it is envisioned that the artificial vdW ferromagnetic platform can artificially inject the ferromagnetism in bulk vdW VSe2, which has not been possible previously.
Yang ; Eric S -R; Lee ; Cheol H; Le ; Hoang-Anh ; Lee ; In-Hwan
Instantons and topological order in two-leg electron ladders: A universality class Journal Article
In: Phys. Rev. B, vol. 111, iss. 20, no. 19, pp. 205144, 2025.
@article{Yang2025,
title = {Instantons and topological order in two-leg electron ladders: A universality class},
author = {Yang and S.-R. Eric and Lee and Hyun Cheol and Le and Hoang-Anh and Lee and In-Hwan},
url = {https://link.aps.org/doi/10.1103/PhysRevB.111.205144},
doi = {10.1103/PhysRevB.111.205144},
year = {2025},
date = {2025-05-29},
urldate = {2025-05-29},
journal = {Phys. Rev. B},
volume = {111},
number = {19},
issue = {20},
pages = {205144},
abstract = {Our numerical study of the disordered Hubbard model with nearest-neighbor hopping shows that a two-leg electron ladder has a finite topological entanglement entropy in the regime where the density of states exhibits an exponentially decaying gap. The value of the topological entanglement entropy suggests that two-leg ladders belong to the same universality class as graphene zigzag nanoribbons, despite several structural differences. A Shankar-Witten-type bosonization Lagrangian with disorder captures several features of the numerically obtained results for disordered two-leg ladders. Additionally, we propose a Lagrangian in which the fusion of two semions residing on different chains generates a fermion (instanton). We apply this Lagrangian within the framework of the pinned charge-density-wave model and compute the relevant Green's function using the bosonization method. This approach predicts a linear density of states at a critical disorder strength. Below this threshold, a soft gap emerges, which is in qualitative agreement with our numerical results.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Our numerical study of the disordered Hubbard model with nearest-neighbor hopping shows that a two-leg electron ladder has a finite topological entanglement entropy in the regime where the density of states exhibits an exponentially decaying gap. The value of the topological entanglement entropy suggests that two-leg ladders belong to the same universality class as graphene zigzag nanoribbons, despite several structural differences. A Shankar-Witten-type bosonization Lagrangian with disorder captures several features of the numerically obtained results for disordered two-leg ladders. Additionally, we propose a Lagrangian in which the fusion of two semions residing on different chains generates a fermion (instanton). We apply this Lagrangian within the framework of the pinned charge-density-wave model and compute the relevant Green's function using the bosonization method. This approach predicts a linear density of states at a critical disorder strength. Below this threshold, a soft gap emerges, which is in qualitative agreement with our numerical results.
Nitz F; Hörandl S; Golibrzuch K; Borodin D; Skoulatakis G; Kandratsenka A; Schwarzer D; Kitsopoulos T N; Auerbach D J; Wodtke A M
Multi-mass velocity-resolved kinetics of surface reactions at 100 kHz acquisition rate Journal Article
In: vol. 96, no. 5, 2025, ISSN: 1089-7623.
@article{Nitz2025,
title = {Multi-mass velocity-resolved kinetics of surface reactions at 100 kHz acquisition rate},
author = {Florian Nitz and Stefan Hörandl and Kai Golibrzuch and Dmitriy Borodin and Georgios Skoulatakis and Alexander Kandratsenka and Dirk Schwarzer and Theofanis N. Kitsopoulos and Daniel J. Auerbach and Alec M. Wodtke},
doi = {10.1063/5.0261106},
issn = {1089-7623},
year = {2025},
date = {2025-05-01},
urldate = {2025-05-01},
volume = {96},
number = {5},
publisher = {AIP Publishing},
abstract = {<jats:p>Velocity-resolved kinetics (VRK) employs a pulsed molecular beam that initiates reactions at a surface and a pulsed ionization-laser that detects desorbed products, exploiting ion-imaging-based, velocity-sensitive detection to derive the product-flux vs reaction time. In its original form, kinetics was observed by scanning the delay between the molecular beam and laser while obtaining ion-images for ions with a single mass-to-charge ratio (m/q). Here, we demonstrate a dramatically improved version of VRK, where data are obtained quasi-continuously with a 100 kHz ionization laser and an event camera based on CERN Timepix3 technology (Amsterdam Scientific Instruments TPX3CAM). This improved version provides the full temporal behavior of the reaction products for every molecular beam pulse, resulting in a duty cycle advantage ranging from ≈ 300 to 105 in the examples given. Furthermore, the new technique allows us to simultaneously follow the kinetics of multiple species with different m/q by using the event camera’s ability to provide pixel-specific timestamps. Data for three example systems, hydrogen atom recombination, hydrogen oxidation, and ammonia oxidation on Pt(332), illustrate the improvements in the acquisition rate and signal-to-noise ratio obtained. We also show that it is possible to extend the application of the VRK technique to non-stationary catalysts.</jats:p>},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
<jats:p>Velocity-resolved kinetics (VRK) employs a pulsed molecular beam that initiates reactions at a surface and a pulsed ionization-laser that detects desorbed products, exploiting ion-imaging-based, velocity-sensitive detection to derive the product-flux vs reaction time. In its original form, kinetics was observed by scanning the delay between the molecular beam and laser while obtaining ion-images for ions with a single mass-to-charge ratio (m/q). Here, we demonstrate a dramatically improved version of VRK, where data are obtained quasi-continuously with a 100 kHz ionization laser and an event camera based on CERN Timepix3 technology (Amsterdam Scientific Instruments TPX3CAM). This improved version provides the full temporal behavior of the reaction products for every molecular beam pulse, resulting in a duty cycle advantage ranging from ≈ 300 to 105 in the examples given. Furthermore, the new technique allows us to simultaneously follow the kinetics of multiple species with different m/q by using the event camera’s ability to provide pixel-specific timestamps. Data for three example systems, hydrogen atom recombination, hydrogen oxidation, and ammonia oxidation on Pt(332), illustrate the improvements in the acquisition rate and signal-to-noise ratio obtained. We also show that it is possible to extend the application of the VRK technique to non-stationary catalysts.</jats:p>
Seung H; Bok J; Kim J S; Kim J; Choi H; Ahn J; Hong J P; Yoon E; Blumstengel S; Kim Y Y; Colazzo L; Park S; Hwang D K; Park J; Choi C; Hyeon T; Kim D
Covalent heterostructures of ultrathin amorphous carbon nitride and Si for high-performance vertical photodiodes Journal Article
In: Nat. Synth, vol. 4, no. 4, pp. 514–522, 2025, ISSN: 2731-0582.
@article{Seung2025,
title = {Covalent heterostructures of ultrathin amorphous carbon nitride and Si for high-performance vertical photodiodes},
author = {Hyojin Seung and Jinsol Bok and Ji Su Kim and Jihoon Kim and Hyeonseung Choi and Jongtae Ahn and Jung Pyo Hong and Eunki Yoon and Sylke Blumstengel and Young Yong Kim and Luciano Colazzo and Soohyung Park and Do Kyung Hwang and Jungwon Park and Changsoon Choi and Taeghwan Hyeon and Dae-Hyeong Kim},
doi = {10.1038/s44160-024-00730-2},
issn = {2731-0582},
year = {2025},
date = {2025-04-04},
journal = {Nat. Synth},
volume = {4},
number = {4},
pages = {514--522},
publisher = {Springer Science and Business Media LLC},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Urdaniz C; Taherpour S; Yu J; Reina-Galvez J; Wolf C
Transition-Metal Phthalocyanines as Versatile Building Blocks for Molecular Qubits on Surfaces Journal Article
In: The Journal of Physical Chemistry A, 2025, ISSN: 1520-5215.
@article{Urdaniz2025,
title = {Transition-Metal Phthalocyanines as Versatile Building Blocks for Molecular Qubits on Surfaces},
author = {Corina Urdaniz and Saba Taherpour and Jisoo Yu and Jose Reina-Galvez and Christoph Wolf},
url = {https://pubs.acs.org/doi/10.1021/acs.jpca.4c07627},
doi = {10.1021/acs.jpca.4c07627},
issn = {1520-5215},
year = {2025},
date = {2025-02-20},
urldate = {2025-02-20},
journal = {The Journal of Physical Chemistry A},
abstract = {The search for molecular or colloidal building units capable of autonomously organized configurations has been a long-standing endeavor that has resulted in the development of innovative material categories, such as metal–organic and covalent organic or long-range molecular networks. In particular, the possibility of using molecules on surfaces to create specific architectures, for example, those containing nanostructures of S = 1/2 molecular spin, can enable versatile quantum materials and the exploration of future quantum devices. Transition-metal phthalocyanines are particularly attractive candidates as they are stable molecules that can host spin-bearing transition-metal ions in a planar conjugated ring. Here, we use density functional theory calculations to systematically study electronic and magnetic properties and hyperfine parameters for the whole series of 3d transition-metal atoms. We perform transport simulations of selected qubit candidates to further elucidate their suitability for molecular spin qubits on a surface.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The search for molecular or colloidal building units capable of autonomously organized configurations has been a long-standing endeavor that has resulted in the development of innovative material categories, such as metal–organic and covalent organic or long-range molecular networks. In particular, the possibility of using molecules on surfaces to create specific architectures, for example, those containing nanostructures of S = 1/2 molecular spin, can enable versatile quantum materials and the exploration of future quantum devices. Transition-metal phthalocyanines are particularly attractive candidates as they are stable molecules that can host spin-bearing transition-metal ions in a planar conjugated ring. Here, we use density functional theory calculations to systematically study electronic and magnetic properties and hyperfine parameters for the whole series of 3d transition-metal atoms. We perform transport simulations of selected qubit candidates to further elucidate their suitability for molecular spin qubits on a surface.
Kim G; Lee J; Seok H; Kang T; Lee M; Choi H; Son S; Cho J; Lee D; Son S; Hwang H; Shin H; Han S; Woo G; Ollier A; Kim Y; Fang L; Lee S; Han G; Jung G; Lee Y; Kim H; Park J; Heinrich A; Jang W; Kwon S J; Kim T
Stochastically Broken Inversion Symmetry of Van der Waals Topological Insulator for Nanoscale Physically Unclonable Functions Journal Article
In: Advanced Materials, iss. 2419927, 2025, ISSN: 1521-4095.
@article{Kim2025,
title = {Stochastically Broken Inversion Symmetry of Van der Waals Topological Insulator for Nanoscale Physically Unclonable Functions},
author = {Gunhyoung Kim and Jinhyoung Lee and Hyunho Seok and Taewoo Kang and Minyoung Lee and Hyunbin Choi and Sihoon Son and Jinill Cho and Dongho Lee and Seowoo Son and Hosin Hwang and Hyelim Shin and Sujeong Han and Gunhoo Woo and Alexina Ollier and Yeon-Ji Kim and Lei Fang and Seunghwan Lee and Gyuho Han and Goo-Eun Jung and Youngi Lee and Hyeong-U. Kim and Jungwon Park and Andreas Heinrich and Won-Jun Jang and Seok Joon Kwon and Taesung Kim},
url = {https://advanced.onlinelibrary.wiley.com/doi/10.1002/adma.202419927},
doi = {10.1002/adma.202419927},
issn = {1521-4095},
year = {2025},
date = {2025-02-18},
urldate = {2025-02-18},
journal = {Advanced Materials},
issue = {2419927},
abstract = {Owing to the exotic state of quantum matter, topological insulators have emerged as a significant platform for new-generation functional devices. Among these topological insulators, tetradymites have received significant attention because of their van der Waals (vdW) structures and inversion symmetries. Although this inversion symmetry completely blocks exotic quantum phenomena, it should be broken down to facilitate versatile topological functionalities. Recently, a Janus structure is suggested for asymmetric out-of-plane lattice structures, terminating the heterogeneous atoms at two sides of the vdW structure. However, the synthesis of Janus structures has not been achieved commercially because of the imprecise control of the layer-by-layer growth, high-temperature synthesis, and low yield. To overcome these limitations, plasma sulfurization of vdW topological insulators has been presented, enabling stochastic inversion asymmetry. To take practical advantage of the random lattice distortion, physically unclonable functions (PUFs) have been suggested as applications of vdW Janus topological insulators. The sulfur dominance is experimentally demonstrated via X-ray photoelectron spectroscopy, hysteresis variation, cross-sectional transmission electron microscopy, and adhesion energy variation. In conclusion, it is envisioned that the vdW Janus topological insulators can provide an extendable encryption platform for randomized lattice distortion, offering on-demand stochastic inversion asymmetry via a single-step plasma sulfurization.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Owing to the exotic state of quantum matter, topological insulators have emerged as a significant platform for new-generation functional devices. Among these topological insulators, tetradymites have received significant attention because of their van der Waals (vdW) structures and inversion symmetries. Although this inversion symmetry completely blocks exotic quantum phenomena, it should be broken down to facilitate versatile topological functionalities. Recently, a Janus structure is suggested for asymmetric out-of-plane lattice structures, terminating the heterogeneous atoms at two sides of the vdW structure. However, the synthesis of Janus structures has not been achieved commercially because of the imprecise control of the layer-by-layer growth, high-temperature synthesis, and low yield. To overcome these limitations, plasma sulfurization of vdW topological insulators has been presented, enabling stochastic inversion asymmetry. To take practical advantage of the random lattice distortion, physically unclonable functions (PUFs) have been suggested as applications of vdW Janus topological insulators. The sulfur dominance is experimentally demonstrated via X-ray photoelectron spectroscopy, hysteresis variation, cross-sectional transmission electron microscopy, and adhesion energy variation. In conclusion, it is envisioned that the vdW Janus topological insulators can provide an extendable encryption platform for randomized lattice distortion, offering on-demand stochastic inversion asymmetry via a single-step plasma sulfurization.
