Title: [Joint CQSE & NCTS Seminar] High-fidelity gates in Rydberg atoms and nonorthogonal coding using spectrally-entangled biphoton source
Speaker: Dr. Hsiang-Hua Jen (Academia Sinica)
Time: May 12, 2023, 14:30-15:30
Place: NCTS Physics Lecture Hall, 4F, Chee-Chun Leung Cosmology Hall, NTU
Online: https://nationaltaiwanuniversity-zbh.my.webex.com/nationaltaiwanuniversity-zbh.my/j.php?MTID=m210715f40b11b5794be46cfbb95824d1

Abstract:
Here I will talk about two recent works on high-fidelity gates in Rydberg
atoms and nonorthogonal coding scheme proposed in a biphoton source. The first work
relates to the performance of two-qubit gates, which is essential and mandatory to build
a large-scale quantum computer. Here we numerically investigate the time-optimal
pulses to generate a high-fidelity Rydberg Cz in a three-level ladder-type atomic system.
By tuning the temporal shapes of Gaussian or segmented pulses, the populations on the
intermediate excited states are shown to be suppressed within the symmetric gate
operation protocol, which leads to a high Bell fidelity up to 0.9998.
The second work relates to a nonorthogonal coding scheme in the spectral modes
of the multiplexed photon pairs, where we present an architecture of multiple channels
enabling a high-capacity transfer of codewords. Using the measures of the second-order
correlations and associated visibility and contrast, we further quantify the performance
of the proposed nonorthogonal coding scheme. Our results demonstrate the capability to
encode and decode quantum information beyond the orthogonal coding scheme and the
feature of error resilience.

Biography:
Dr. Hsiang-Hua Jen:
-Mar 2020 – present Assistant research fellow, IAMS of Academia Sinica, Taiwan.
-Aug 2017 – Feb 2020 Assistant research scholar, IOP of Academia Sinica, Taiwan.
-Aug 2014 – July 2017 Postdoc, IOP of Academia Sinica, Taiwan.
-Aug 2013 – July 2014 Postdoc, TU of Kaiserslautern, Germany.
-Mar 2011 – July 2013 Postdoc, NTHU, Taiwan.
-Jan 2005 – Dec 2010 Doctorate, Physics, Georgia Institute of Technology.
-Aug 2003 – Dec 2004 MS, Physics, Georgia Institute of Technology.
-Jun 1996 – Jun 2000 BS, Physics, National Taiwan University.

· 2019 IOP Outstanding Reviewer for Journal of Physics B: Atomic, Molecular and Optical Physics

· Paper [Phys. Rev. A 95, 043840 (2017)] selected as Kaleidoscope in the issue of April 2017

2014 NCTS Best postdoc paper award, Taiwan 
2012 NSC (now MOST) Postdoc academic publication award, Taiwan
1996 ROC national contest for Asian Pacific Mathematics Olympiad (40 contestants nationally)