
This colloquium series explores different aspects of both quantum and nanoscience with the aim of expanding participants’ thinking by spurring curiosity. You are welcome to join us as our distinguished guest scholars lecture about their cutting-edge research findings; compelling musings; and intellectual hedonism.
Registration is required! Please, register here.
Upcoming Events

Aug 2023
On-site (Center for Quantum Nanoscience) with Live-streaming
Alec Wodtke
Title: Condensed phase isomerization through tunneling gateways
Event Details
Alec Wodtke Affiliation: Max Planck Institute for Multidisciplinary Sciences Date: Aug 11th (Fri), 2023 (17:00 - 18:00, KST) (10:00 -11:00, CET) Title: Condensed phase tunneling
Event Details
Alec Wodtke
Affiliation: Max Planck Institute for Multidisciplinary Sciences
Date: Aug 11th (Fri), 2023 (17:00 – 18:00, KST) (10:00 -11:00, CET)
Title: Condensed phase tunneling from Enzyme Kinetics to Astrochemistry
Abstract: Superconducting nanowire single-photon detectors (SNSPDs) provide sufficient sensitivity to enable laser-induced fluorescence (LIF) experiments in the mid-infrared, an exciting technical development for studying molecule-surface interactions. In this talk, I will present results of experiments on the vibrational dynamics of monolayers and multilayers of solid CO adsorbed at the surface of a NaCl crystal that provide observations of quantum state resolved dynamics. When, for example, a pulsed ns laser excites CO to its v=1 state, a monochromator equipped with an SNSPD detects wavelength- and time-resolved mid-infrared emission from CO vibrational states up to v=27 that are produced by vibration-vibration (V-V) energy transfer. Kinetic Monte Carlo (kMC) simulations show that vibrational energy collects in a few CO molecules at the expense of those up to eight lattice sites away. The excited CO molecules relax by a mechanism resembling Sommerfeld’s theory of ground waves important to radio wave propagation, losing their energy to NaCl lattice-vibrations via the electromagnetic near-field. This is a weak coupling limit, where the potential energy surface is not needed to describe the relaxation process.
At high resolution, we observe new lines appearing in the infrared emission spectra, showing that CO vibrational energy converts “the right side up” where CO is bound by its C-atom to the surface to an “upside down” metastable isomer. Flipping back involves thermally activated tunneling, exhibiting a large isotope effect, where the lightest isotope is not the fastest tunneller. This is explained by a quantum rate theory of isomerization involving tunneling gateways. Near resonant states, localized on opposite sides of the isomerization barrier are coupled by collisions with a phonon bath. This represents an alternative to traditional tunneling pictures like Instanton and WKB, which are based on continuum scattering picture that is not valid in condensed phases.
*Arnab Choudhury 1,2, Jessalyn Devine 1, Dirk Schwarzer 1, Shreya Sinha 3, Peter Saalfrank 3, Alec Wodtke 1,2 1 Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany 2 Institute for physical chemistry, University of Göttingen, Göttingen, Germany 3 University of Potsdam, Potsdam Germany See Choudhury et al., Nature 612, 691–695 (2022)
To participate in the talk, please, fill out the Registration Form →
Time
(Friday) 5:00 pm - 6:00 pm (KST)
Location
Center for Quantum Nanoscience
Research Cooperation Building,52 Ewhayeodae-gil, Daehyeon-dong

Aug 2023
On-site (Center for Quantum Nanoscience) with Live-streaming
Wilson Ho
Title: TBA
Event Details
Wilson Ho Affiliation: University of California, Irvine Date: Aug 16th (Wed), 2023 (17:00 - 18:00, KST) (10:00 -11:00, CET) Title: A Qubit-Based Quantum Microscope for
Event Details
Wilson Ho
Affiliation: University of California, Irvine
Date: Aug 16th (Wed), 2023 (17:00 – 18:00, KST) (10:00 -11:00, CET)
Title: A Qubit-Based Quantum Microscope for Space-Time Sensing
Abstract: In contrast to all other microscopes, a qubit-based quantum microscope (QM) combining coherent light with the scanning tunneling microscope (STM) is unique in incorporating the quantum superposition principle in its operation. This QM uses the superposition of two levels in a single hydrogen molecule as the sensor to probe the electric fields of a sample’s surface. In a pilot study (Science 376, 401, 2022; Phys. Rev. Lett. 130, 096201, 2023) the QM demonstrates a 300-fold finer energy resolution and 0.1 angstrom spatial sensitivity of the sample’s near-field electrostatics, compared to microscopes not based on this quantum principle. Furthermore, the wave-particle duality, nonlinear Stark effects, superposition of multiple quantum states, and entanglement among adjacent two levels illustrate the sensitivity of the QM to a set of basic phenomena underlying quantum mechanics. This qubit-based QM advances precision measurement with space-time resolution by irradiating the STM junction with femtosecond THz radiation and recording in the time domain coherent oscillations of the light-induced rectified tunneling current. The common occurrence of systems with two levels within a double-well potential suggests a broad application of the QM in probing the heterogeneous distribution of static and dynamic properties of electrons in functional materials.
To participate in the talk, please, fill out the Registration Form →
Time
(Wednesday) 5:00 pm - 6:00 pm (KST)
Location
Center for Quantum Nanoscience
Research Cooperation Building,52 Ewhayeodae-gil, Daehyeon-dong
Past Events

May 2023
On-site (Center for Quantum Nanoscience) with Live-streaming
Philip Kim
Title: Engineered quantum materials using van der Waals atomic layer heterostructures
Event Details
Philip Kim Affiliation: Harvard University Date: May 17, 2023 (15:00 - 16:00, KST; Wednesday) (8:00, CET; Wednesday) (23:00, PDT; Tuesday) Title: Engineered quantum materials using
Event Details
Philip Kim
Affiliation: Harvard University
Date: May 17, 2023 (15:00 – 16:00, KST; Wednesday) (8:00, CET; Wednesday) (23:00, PDT; Tuesday)
Title: Engineered quantum materials using van der Waals atomic layer heterostructures
Abstract:
Over the last 50 years, two-dimensional (2D) electron systems have served as a key material platform for the investigation of fascinating quantum phenomena in engineered material systems. Recently, scientists have found that it is feasible to produce van der Waals (vdW) layered materials that are atomically thin. In these atomically thin materials, quantum physics enables electrons to move effectively only in a 2D space. Additionally, by stacking these 2D quantum materials, it is also possible to create atomically thin vdW heterostructures with an extensive range of interfacial electronic and optical properties. Novel 2D electronic systems realized in vdW atomic stacks have served as an engineered quantum material platform. In this presentation, we will discuss several research initiatives aimed at realizing emergent physical phenomena in stacked vdW interfaces between 2D materials.
To participate in the talk, please, fill out the Registration Form →
Time
(Wednesday) 3:00 pm - 4:00 pm (KST)
Location
Center for Quantum Nanoscience
Research Cooperation Building,52 Ewhayeodae-gil, Daehyeon-dong

Feb 28th, 2023
On-site (Center for Quantum Nanoscience) with Live-streaming
Nicolas Lorente
Title: The Kondo effect as revealed by STM measurements
Event Details
Nicolas Lorente Affiliation: CFM – Materials Physics Center Date: Feb 28th, 2023 (17:00 - 18:00, KST) (09:00 -10:00, CET) Title: The Kondo effect as revealed
Event Details
Nicolas Lorente
Affiliation: CFM – Materials Physics Center
Date: Feb 28th, 2023 (17:00 – 18:00, KST) (09:00 -10:00, CET)
Title: The Kondo effect as revealed by STM measurements
Abstract:
The ground state of a metal is, to a great degree of accuracy, well described by one-electron states. However, as soon as there is a magnetic interaction that can change the spin of the electrons, the ground state becomes a very complex state. The reason for this is the development of a multielectronic state that cannot be separated in single states. Magnetic impurities are efficient at mixing electronic spins and the new emerging ground state is the hallmark of the Kondo effect. To this respect, the scanning tunneling microscope (STM) is an excellent tool to interrogate the electronic correlations induced by the magnetic impurities. It can locally study the magnetic impurities on metallic substrate and it can reveal the properties of the electronic states essential for the Kondo state [1]. In this Colloquium, I will review the main features of the Kondo effect and how they have been revealed by STM experiments. Moreover, I will analyze some recent results obtained in my group in collaboration with experimental colleagues. In the spirit of a Colloquium talk, the exposition will be pedagogical, emphasizing physical results over formal theoretical considerations.
The first case will be the study of Manganese phthalocyanines on different metallic substrates. Manganese phathalocyanines are S=3/2 magnetic molecules that present orbital and spin degeneracies. Here, the Kondo effect is efficiently mixed with orbital excitations [2]. The second topic will be about Nickelocene molecules that are also magnetic, but their ground state is S=1 and the Kramers theorem does not apply. The spin degeneracy is lifted and no Kondo effect is detectable and instead spin-flip excitations are strong signals in the experimental spectra [3]. In this case, the competing excitations are vibrations. The joint Kondo plus vibrational excitation reveal some astonishing features [4]. Finally, even in the case of a pure S=1/2 cobaltocene molecule, the Kondo spectra becomes strongly modified by the presence of molecular vibrations [5].
References :
[1] D.-J. Choi and N. Lorente, Handbook of Materials Modeling: Applications: Current and Emerging Materials, p. 467, Springer International Publishing (2020).
[2] Jens Kügel et al. Phys. Rev. Lett. 121, 226402 (2018)
[3] Benjamin Verlhac et al. Science 366, 623 (2019)
[4] Nicolas Bachelier et al. Nature Comm. 11, 1619 (2020)
[5] Léo Garnier et al. Nano Letters 20, 8193 (2020).
To participate in the talk, please, fill out the Registration Form →
Time
(Tuesday) 5:00 pm - 6:00 pm (KST)
Location
Center for Quantum Nanoscience
Research Cooperation Building,52 Ewhayeodae-gil, Daehyeon-dong

Dec 2022
On-site (Center for Quantum Nanoscience) with Live-streaming
Harald Brune
Title: Exploring the Magnetic Quantum States of Single Surface Adsorbed Atoms
Event Details
Harald Brune Affiliation: École Polytechnique Fédérale de Lausanne (EPFL) (Swiss Federal Institute of Technology Lausanne) Date: Dec 7th, 2022 (17:00 KST; 09:00 CET) Title: Exploring
Event Details
Harald Brune
Affiliation: École Polytechnique Fédérale de Lausanne (EPFL) (Swiss Federal Institute of Technology Lausanne)
Date: Dec 7th, 2022 (17:00 KST; 09:00 CET)
Title: Exploring the Magnetic Quantum States of Single Surface Adsorbed Atoms
Abstract:
The magnetic properties of single surface adsorbed atoms became one of the core interests in surface and nanoscience in 2003, where single Co atoms on Pt were reported to have 200 times the magnetic anisotropy energy of bulk Co [1]. Years later, even 1000 times this energy was reached for single Co atoms on thin MgO films [2]. In a classical picture, this suggests that these single atoms should be rather stable magnets. However, despite numerous efforts, the magnetic quantum states of all investigated single surface adsorbed transition metal atoms had very short magnetic relaxation times, below 1 µs.
Immediately after changing to rare-earth atoms, a few adsorbate/substrate combinations could be identified, where the magnetization vector of a single atom is indeed stable over hours in the absence of an external magnetic field [3,4]. Therefore, these systems are single atom magnets and enable magnetic information storage in the smallest unit of matter. We will give an overview over the present adsorbate/substrate systems exhibiting single atom magnet behavior [3 – 7] and explain the essential ingredients for this surprising stability of single spin systems that are exposed to numerous perturbations from the environment. These atoms can be placed very close and still individually be addressed conceptually enabling information storage at densities by 3 orders of magnitude larger than presently used devices.
Now the fundamental research field turns its attention to quantum coherent spin operations in single surface adsorbed atoms. If they have long enough coherence times with respect to the time it takes to perform a single quantum spin operation, these would be single atom quantum bits. The requirements for long coherence times of the magnetic quantum states are quite different from the ones of magnetic relaxation times. We will illustrate this with a few examples and point out single rare-earth atom systems that lend themselves already now as quantum repeaters in telecommunication [8], creating hope that single atom qubits may indeed become reality in the near future.
[1] P. Gambardella et al. Science 300, 1130 (2003).
[2] I. G. Rau et al. Science 344, 988 (2014).
[3] F. Donati et al. Science 352, 318 (2016).
[4] R. Baltic et al. Nanolett. 16, 7610 (2016).
[5] A. Singha et al. Nat. Communic. 12, 4179 (2021).
[6] F. Donati et al. Nano Lett. 21, 8266 (2021).
[7] V. Bellini et al. ACS Nano 16, 11182 (2021).
[8] M. Zhong et al. Nature 517, 177 (2015).
To participate in the talk, please, fill out the Registration Form →
Time
(Wednesday) 5:00 pm - 6:00 pm (KST)
Location
Center for Quantum Nanoscience
Research Cooperation Building,52 Ewhayeodae-gil, Daehyeon-dong

Oct 2022
On-site (Center for Quantum Nanoscience) with Live-streaming
Jeremy Levy
Title: Correlated Nanoelectronics and the Second Quantum Revolution
Jeremy Levy Affiliation: University of Pittsburgh Date: Oct 17th, 2022 (17:00 - 18:00, KST) Title: Correlated Nanoelectronics and the Second Quantum Revolution Abstract: Strongly correlated electronic materials and Affiliation: University of Pittsburgh Date: Oct 17th, 2022 (17:00 – 18:00, KST) Title: Correlated Nanoelectronics and the Second Quantum Revolution Abstract: Strongly correlated electronic materials and quantum transport of nanoelectronic systems are areas of research that have traditionally followed non-intersecting paths. With the development of complex-oxide heterostructures and nanostructures, a nascent field of Correlated Nanoelectronics has emerged. My research program makes extensive use of nanoscale reconfigurability of a complex-oxide heterostructure formed from a thin layer of LaAlO3 grown on SrTiO3. Like an Etch-a-Sketch toy, the LaAlO3/SrTiO3 interface can be drawn (and erased) with 2 nm resolution to create a remarkable range of quantum devices. These nanoscale devices can be “aimed” back at the materials themselves to provide insight into their inner workings. This platform has already produced two novel phases of electronic matter: one in which electrons form bound pairs without becoming superconducting, and a family of one-dimensional degenerate quantum liquids formed from n-tuples of bound electrons. A rich and growing palette of quantum building blocks is currently being explored for applications in quantum computing, quantum simulation, and quantum sensing, major goals of the Second Quantum Revolution. To participate in the talk, please, fill out the Registration Form → (Monday) 5:00 pm - 6:00 pm (KST) Center for Quantum Nanoscience Research Cooperation Building,52 Ewhayeodae-gil, Daehyeon-dongEvent Details
Event Details
Jeremy Levy
Time
Location

Zoom (Online)
Ali Yazdani
Title: Correlation, Topology, and Unconventional Superconductivity in a Moiré Material
Event Details
Ali Yazdani Affiliation: Princeton University Date: May 31th, 2022 Title: Correlation, Topology, and Unconventional Superconductivity in a Moiré Material Video link: https://youtu.be/WeSo2IXsW0Q
Event Details
Ali Yazdani
Affiliation: Princeton University
Date: May 31th, 2022
Title: Correlation, Topology, and Unconventional Superconductivity in a Moiré Material
Video link: https://youtu.be/WeSo2IXsW0Q
Time
(Tuesday) 9:00 am - 10:00 am (KST)
Location
ZOOM Application
Online (Zoom)
Andrea Morello
Quantum information and quantum foundations with spins in silicon
Event Details
Andrea Morello Affiliation: University of New South Wales Date: May 25, 2021; 17:00 - 18:30 Quantum information and quantum foundations with spins in silicon Link: https://youtu.be/6L5qt3v_Eqw
Event Details
Andrea Morello
Affiliation: University of New South Wales
Date: May 25, 2021; 17:00 – 18:30
Quantum information and quantum foundations with spins in silicon
Time
(Tuesday) 5:00 pm - 6:30 pm KST
Location
ZOOM Application