学术报告第163期：Quantum state tomography and decoherence effects in non-Hermitian open systems

主讲人 (Speaker): 

Yogesh Narayan Joglekar

主讲人单位 (Speaker's Institute): 

Indiana University-Purdue University

邀请人 (Invited by): 

罗乐

时间 (Time): 

星期二, 2019/12/17 - 09:00 to 11:00

地点 (Location): 

珠海校区海滨红楼17栋107 (Rm 107, Red House 17)

摘要 (Abstract): 

Open systems with gain and loss, described by non-Hermitian Hamiltonians, have been a subject of intense research. In classical systems, the effect of their exceptional-point (EP) degeneracies has been observed through remarkable phenomena such as the parity-time symmetry breaking transition. However, the consequences of an EP for quantum evolution and decoherence are unexplored. Here, we will show how evolution under a non-Hermitian Hamiltonian is extracted from the traditional Lindblad dynamics. We will use post-selection on a three-level superconducting transmon circuit with tunable Rabi drive, dissipation, and detuning to carry out quantum state tomography of a single dissipative qubit in the vicinity of its EP. Quantum state tomography reveals the PT symmetry breaking transition at zero detuning, decoherence enhancement at finite detuning, and a quantum signature of the EP in the qubit relaxation state. Our observations demonstrate rich phenomena associated with non-Hermitian physics in the fully quantum regime and open routes to explore and harness exceptional point degeneracies for enhanced sensing and quantum information processing.

主讲人简介 (Speaker's CV): 

Education: • 1996-2001: Ph.D. Physics, Indiana University, Bloomington, USA. Thesis advisor: Prof. Allan H. MacDonald. • 1991-1996: M.Sc. (Integrated) Physics, Indian Institute of Technology, Kanpur, India. Employment: • 2012-present: Associate Professor of Physics, Indiana University Purdue University Indianapolis (IUPUI), Indianapolis, USA. • December 2005-2012: Assistant Professor of Physics, IUPUI, Indianapolis, USA. • September 2002-November 2005: Postdoctoral Research Associate, Los Alamos National Laboratory, USA. (Postdoctoral advisor: Dr. Alexander V. Balatsky.) • December 2001-August 2002: Postdoctoral Fellow, University of Kentucky, Lexington, USA. (Postdoctoral advisor: Prof. Ganpathy Murthy.) Honors and Awards: • Benjamin Meaker Visiting Professor, University of Bristol, UK (2013). • Theoretical research in my group carried out with high-school students was featured in a Turning Point Q & A (Nature 494, 139 (2013)). • Kavli Institute of Theoretical Physics (KITP) Scholar (2013-2015). • Theory research with Jacob L. Barnett, age 11, was featured in a CBS 60 Minutes news segment on him (2012). • National Science Foundation (NSF) CAREER award (2011). Research Interests: • Quantum simulations of closed and open systems. • Parity-Time (PT) symmetry and its realizations in classical and quantum domains. • Meaningfully engaging young students in theoretical physics research. Recent Invited Presentations: • Plenary: XV Latin American Workshop on Nonlinear Phenomena (La Serena, Chile 2017). • META: International Conference on Metamaterials, Photonics, and Plasmonics (South Korea 2017; Malaga, Spain 2016; New York 2015). • Pseudo-Hermitian Hamiltonians in Quantum Physics (PHHQP) (Bengaluru, India 2018; Bad Honnef, Germany 2017; Kyoto, Japan 2016; Jerusalem 2015). • Analytical and Algebraic Methods in Physics (Prague 2017, 2016). • Emergent Paradigms in Nonlinear complexity, CNLS and Santa Fe Institute (2017). • University of Washington St. Louis (2017); University of Illinois at Urbana Champaign (2017); Los Alamos National Laboratory (2018, 2017, 2015); Sun Yat-Sen University, Zhuhai, China (2017); Southeast University, Nanjing, China (2017); Catholic University of Valparaiso, Chile (2017). • Winter School Lectures: Taller de Optica cuantica 2016 (Mexico, 2016). • Invited Outreach Lectures: Taste of Science: public outreach festival, Indianapolis (2017); Science on Tap! seminar “Exploring Quantum Weirdness with Kids” (2015).