Time-Reversal-Symmetry-Breaking Superconductivity in Epitaxial Bismuth/Nickel Bilayers

Superconductivity that spontaneously breaks time-reversal symmetry (TRS) has been found, so far, only in a handful of 3D crystals with bulk inversion symmetry. Here we report an observation of spontaneous TRS breaking in a 2D superconducting system without inversion symmetry: the epitaxial bilayer films of bismuth and nickel. The evidence comes from the onset of the polar Kerr effect at the superconducting transition in the absence of an external magnetic field, detected by the ultrasensitive loop-less fiber-optic Sagnac interferometer.

Realizing quantum advantage without entanglement in single-photon states

Lunch served at 12:00
 
Quantum Discord expresses quantum correlations beyond those associated with entanglement. Although its theory has been extensively studied, quantum discord has yet to become a standard tool in experimental studies of correlations. We propose an optical circuit for  attaining quantum measurement advantage in a system that has no  quantum entanglement.  Our device

Trapped ions as a quantum spin glass annealer

Lunch served at 12:00

Solving spin glass models is a complex, often NP-hard, task. In this talk, I will discuss a strategy to attack this problem using trapped ions as a flexible emulator of spin Hamiltonians. Studying its dynamics in a slowly decaying magnetic field, such system can be used as a quantum annealer which might be capable of solving hard optimization problems in polynomial time.