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Bild: Lingzhen Guo

Dr. Lingzhen Guo

Gruppe: Schön
Raum: 10-20
Tel.: +49 721 608-43370
Fax: +49 721 608-47040
lzguoOhf9∂tfp uni-karlsruhe de

Institut für Theoretische Festkörperphysik
Karlsruher Institut für Technologie (Universität)
Wolfgang-Gaede-Str. 1
D-76128 Karlsruhe
Germany



 

Research Directions

  • Quantum Theory:

  1. Driven Nonlinear Systems: Quantum fluctuations, Multistability and Switching rate.
  2. Giant Artificial Atoms: Time-delay and Memory effects in quantum systems, Quantum optics in new regimes.
  3. New Physics by Floquet Engineering: Topology & Many-body Physics in Phase Space Lattices, Dynamical Crystals

                           

  • Quantum Technology:

  1. Superconducting quantum circuits, Circuit QED (Circuit Quantum Electro-Dynamics)
  2. Hybrid quantum systems, Circuit QAD (Circuit Quantum Acoustic-Dynamics), Quantum (opto-)mechanical systems
  3. Quantum measurement & feedback control, Quantum computing and Quantum simulation

Research Experiences

2015.09-Present: Responsible for a junior research group funded by Carl-Zeiss-Stiftung @ TFP, KIT, Germany

 o Topics: Floquet Physics & Engineering, Topology and Quantum Many-body Physics, Quantum Optics with superconducting circuits

 o Results: We explore the possible new physics by Floquet engineering. Using ultracold atoms in stroboscopic 1D optical lattice, we propose the concept of Dynamical Crystals and Topology & Many-body Physics in Phase Space Lattices. We also investigate the quantum optics and microwave photonics with superconducting circuits, especially the effects related to the size of artificial atoms: time-delay effects in quantum systems. 

 

 2014.09-2015.08: Postdoc @ MC2, Chalmers University of Technology, Sweden

 o Topics: Quantum Acoustics with Surface Acoustic Waves

 o Results: We work on a hybrid system, which couples the transmon in circuit QED to the propagating mechanical modes of Surface Acoustic Wave (SAW). This is an analogue of circuit QED system but replacing the microwave photons by SAW phonons. We find the transmon decays polynomially rather than exponentially in the phonon bath. We calculate the second order correlation function in the weak driving limit.

 o Main Collaborators: Prof. Göran Johansson, Dr. Anton Frisk Kockum, Prof. Per Delsing's experimental group

 

 2010.09-2014.08: 3-year PhD student and 1-year Postdoc @ TFP, Karlsruhe Institute of Technology (KIT), Germany

 o Topics: Periodically driven quantum system, Floquet physics

 o Results: The first topic we are interested in is the environment's dissipation-induced switching rate, between the multiple meta-stable states in periodically driven system. The switching rate behaves qualitatively differently in the semiclassical regime and quantum regime. Our work identifies there is also a crossover regime and calculates the corresponding quantum critical temperature [PRA 87, 062117(2013)]. The second topic we focus on is the dynamical tunnelling between multiple meta-stable states. Our work connects the periodic structure of periodically driven system in phase space to the solid state physics. We propose the idea of phase space crystals [PRL 111, 205303 (2013)]. This may provide a new way to simulate the condense matter phenomena by synthesizing lattice structures in phase space [New J. Phys. 18 (2016) 023006].

 o Main Collaborators: Dr. Michael Marthaler, Dr. Vittorio Peano, Prof. Mark Dykman, Prof. Gerd Schön

 

 2008.06-2010.08: Graduate student @ Department of Physics, Beijing Normal University, China

 o Topics: Quantum measurement, Quantum feedback control, Quantum trajectory theory

 o  Results: In the direction of quantum measurement, we focus on the topic of measuring errors due to the thermal and quantum fluctuations in Josephson Bifurcation Amplifier (JBA). Using the quantum master equation method, we find there is a linear scaling behaviour of measuring error rate near the bistability critical point in the deep quatum regime [EPL, 90 (2010) 10011, PRE 84, 011144 (2011)], diffrent from the 3/2-power law in the semiclassical regime. In the direction of quantum feedback control, we work on the topic of qubit state engineering in circuit QED system. Based on the method of quantum trajectory theory, we propose how to deterministically create and stabilize two-qubit entanglement states in circuit QED by homodyne-mediated feedback control [PRA 82, 032335 (2010)].

 o Main Collaborators: Prof. Xinqi Li, Prof. Zhigang Zhen, Prof. Yijin Yan

 

Grants and Scholarships

  • Carl-Zeiss-Stiftung Nachwuchsprogramm 2015 zur Förderung von Postdoktorand    

             Synthesizing Lattice Structure in Phase Space

 
             Partners: Dr. Lingzhen Guo, Dr. Michael Marthaler, Pengfei Liang (PhD student)


             Period: Sept. 2015 - Aug. 2017 

 

  • KHYS Visiting Researcher Scholarship, KIT

             Partners: Dr. Lingzhen Guo, Modan Liu (master student)


             Period: 01.04.2014 – 30.09.2014

 

  • Chinese Government Scholarship for Studying Abroad, 09.2010-08.2012
  • Individuelle Förderung für Doktoranden aus dem Ausland-DAAD-STIBET, 12.2010-05.2011​ 

 

 

 

Positions

09. 2015 — present     Postdoc, TFP, Karlsruhe Institute of Technology (KIT), Germany

09. 2014 — 08. 2015   Postdoc, MC2, Chalmers University of Technology, Sweden

07. 2013 — 08. 2014   Postdoc, TFP, Karlsruhe Institute of Technology (KIT), Germany

06. 2010 — 08. 2010   Research Assistant, Department of Chemistry, Hong Kong Uni. of Science and Technology, Hong Kong

  

Education

07.2013                       PhD thesis defended in BNU, Thesis title: Quantum Effects in Driven Nonlinear Systems

09.2010 — 08.2012     Studying in KIT  supported by Chinese Government Scholarship

09.2009 — 08.2013     PhD student,

                                    Department of Physics, Beijing Normal University (BNU), Beijing, China

                                    TFP, Karlsruhe Institute of Technology (KIT), Germany

09.2006 — 07.2009     Master student, Department of Physics, Beijing Normal University (BNU), Beijing, China

09.2001 — 07.2005     Undergraduate Student, Department of Physics, Beijing Normal University (BNU), Beijing, China

 

Publications

2017

Regular Articles
Titel Autor Journal
Giant acoustic atom: a single quantum system with a deterministic time delay L. Guo, A. Grimsmo, A. Frisk Kockum, M. Pletyukhov and G. Johansson Phys. Rev. A (Editors' Suggestion) 95, 053821 (2017)

2016

Regular Articles
Titel Autor Journal
Effective Long-distance Interaction from Short-distance Interaction in Periodically Driven One-dimensional Classical System L. Guo, M. Liu and M. Marthaler Phys. Rev. A 93, 053616 (2016)
Synthesizing Lattice Structure in Phase Space L. Guo and M. Marthaler New J. Phys. 18, 023006 (2016)

2015

Regular Articles
Titel Autor Journal
Multi-photon dressing of an anharmonic superconducting many-level quantum circuit J. Braumüller, J. Cramer, S. Schlör, H. Rotzinger, L. Radtke, A. Lukashenko, P. Yang, M. Marthaler, L. Guo, A.V. Ustinov and M. Weides Phys. Rev. B 91, 054523 (2015)

2013

Dissertations
Titel Autor Journal
Quantum Effects in Driven Nonlinear Systems L. Guo May, 2013
Regular Articles
Titel Autor Journal
Phase Space Crystals: A New Way to Create a Quasienergy Band Structure L. Guo, M. Marthaler and G. Schön Phys. Rev. Lett. 111, 205303 (2013)
Quantum critical temperature of a modulated oscillator L. Guo, V. Peano, M. Marthaler and M.I. Dykman Phys. Rev. A 87, 062117 (2013)

2012

Regular Articles
Titel Autor Journal
Emission spectrum of the driven nonlinear oscillator S. André, L. Guo, V. Peano, M. Marthaler and G. Schön Phys. Rev. A 85, 053825 (2012)
Conference Proceedings (contributed)
Titel Autor Journal
The role of damping for the driven anharmonic quantum oscillator L. Guo, M. Marthaler, S. André and G. Schön J. Phys.: Conf. Ser. 400, 042014 (2012)

2011

Regular Articles
Titel Autor Journal
Dynamic Quantum Tunneling in Mesoscopic Driven Duffing Oscillators L. Guo, Z. Zheng, X.Q. Li and Y. Yan Phys. Rev. E 84, 011144 (2011)