We seek physical principles and methods for coherent manipulation of quantum states of mesoscopic systems, and study
the effects of such manipulation on various phenomena including quantum transport and quantum information processing.
More specific fields are:
- Quantum Computation and Quantum Information.
- Quantum Transport in Mesoscopic Systems.
- Superconductivity and Superconducting Quantum Circuits.
- Spin Transport and Quantum Information Processing with Spins.
Research Highlights
Negative Tunneling Magneto-Resistance (TMR) in LAO/STO
- Jun 12, 2015
- Nature Communications (2015)
The spin selection rule prevents up-spin electrons from tunneling to the sea of down-spin electrons. This leads to positive tunneling magneto-resistance (TMR). In a coming article of Nature Communications, a KRISS team led by Dr. Jinhee Kim reports experimentally and Mr. Seungju Han and Professor Mahn-Soo Choi of KU Physics explain theoretically an exotic negative and anisotropoic TMR in LAO/STO interface. LAO/STO interface is remarkable in that it can be superconducting and ferromagnetic at the same time.
Majorana Stands Out In A Quantum Rc Circuit
- Aug 27, 2014
- Phys Rev Lett 113 (7), 076801 (2014)
Majorana is an exotic fermion that is its own anti-particle. Neutrino is argued to be the only elementary particle of such kind and yet to be confirmed. Majorana as an elementary excitation has been witnessed in condensed matters and yet to be verified.
In a recent Physics Review Letters paper, Prof. Mahn-Soo Choi in KU Physics and his collaborator Prof. Minchul Lee at Kyung Hee University reveal another striking traits of Majoranas that can be seen in a quantum RC circuit.
Seeking Majorana Fermions
- Sep 30, 2011
- Physical Review Letters 107, 136403 (2011)
Domain walls between superconducting and magnetic regions placed on top of a topological insulator support transport channels for Majorana fermions. We propose to study noise correlations in a Hanbury Brown–Twiss type interferometer and find three signatures of the Majorana nature of the channels. First, the average charge current in the outgoing leads vanishes. Furthermore, we predict an anomalously large shot noise in the output ports for a vanishing average current signal. Adding a quantum point contact to the setup, we find a surprising absence of partition noise which can be traced back to the Majorana nature of the carriers.