Current graduate students

Hao Qin, Telecom ParisTech

We report a quantum hacking strategy on a Continuous-Variable (CV) Quantum Key Distribution (QKD) system by inserting an external light. In the implementations of CV QKD systems, transmitting openly local oscillator pulses is a potential vulnerability for an eavesdropper to launch side channel attacks. In this work, other than targeting on local oscillator, we concern two imperfections in a balanced homodyne detector used in CV QKD system: the imbalance in the beam splitter and the finite linear detection limit.

Jamie Sikora, Centre for Quantum Technologies, National University of Singapore

In this talk, I will discuss correlations that can be generated by performing local measurements on bipartite quantum systems. I'll present an algebraic characterization of the set of quantum correlations which allows us to identify an easy-to-compute lower bound on the smallest Hilbert space dimension needed to generate a quantum correlation. I will then discuss some examples showing the tightness of our lower bound.

Juan Miguel Arrazola of the Department of Physics and Astronomy will be defending his thesis:

Practical Quantum Communication

Juan Miguel is supervised by Professor Norbert Lütkenhaus.

Chris Granade, University of Sydney

In recent years, Bayesian methods have been proposed as a solution to a wide range of issues in quantum state and process tomography. In this talk, we make these methods practical by solving three distinct problems: numerical intractability, a lack of informative prior distributions, and an inability to track time-dependent processes. Our approach allows for practical computation of point and region estimators for quantum states and channels, and allows tracking of time-dependent states.

Anirudh of the Department of Physics and Astronomy will be defending his thesis:

Experimentally Testable Noncontextuality Inequalities via Fourier-Motzkin Elimination.

Jihyun is supervised by Professors Joseph Emerson and Robert Spekkens.

Jihyun Park of the Department of Physics and Astronomy will be defending his thesis:

Emulation of Anyonic Statistics using High-Fidelity NMR Quantum Information Processing (QIP) Techniques.

Jihyun is supervised by Professor Raymond Laflamme.

Ibrahim Nsanzineza, Syracuse University

Nonequilibrium quasiparticles and trapped magnetic flux vortices can significantly impact the performance of superconducting microwave resonant circuits and qubits at millikelvin temperatures. Quasiparticles result in excess loss, reducing resonator quality factors and qubit lifetimes. Vortices trapped near regions of large microwave currents also contribute excess loss. However, vortices located in current-free areascan actually trap quasiparticles and lead to a reduction in the quasiparticle loss.

Ying Dong, Hangzhou Normal University

Thermodynamics has been highly successful, impacting strongly on the natural sciences and enabling the development of technologies that have changed our lives, from fridges to jet planes. Until recently, it was applied to large systems described by the laws of classical physics. However, with modern technologies miniaturizing down to the nanoscale and into the quantum regime, testing the applicability of thermodynamics in this new realm has become an exciting technological challenge.

Nitin Jain, Northwestern University

Quantum-optical frequency conversion (QFC) provides a method, usually via a nonlinear interaction with an optical ‘pump’ beam, to keep the quantum features of an optical ‘signal’ intact. Most QFC experiments
upconvert near-infrared signal photons to those in the visible or near-visible regime due to the availability of highly-efficient detectors that can be operated at high speeds without incurring a severe noise penalty.

 John Martinis, University of California,
Santa Barbara

As microelectronics technology nears the end of exponential growth over time, known as Moore’s law, there is a renewed interest in new computing paradigms. I will discuss recent research at UCSB on superconducting quantum bits, as well as our recent start at Google to build a useful quantum computer to solve machine learning problems.  A recent experiment will be highlighted that extends the lifetime of a qubit state using quantum error correction.