Jayameenakshi Venkatraman: Destructive Quantum Interference of Tunnel Paths Reveals Hidden Symmetry

Abstract:

In a quantum world, there is always a path to escape from a trap, thanks to the quantum tunnel effect. Counterintuitively, if another path is also available, the escape paths can be arranged so they destroy each other and completely block the escape way out, thanks to the quantum interference effect. When tunneling across the classically forbidden region is coherently canceled for the ground state, the only path to escape is to climb the walls of the trap and tunnel through the excited states. This is, unless quantum effects also destroy the escape ways through the excited states.

In this talk, I will report on a recent work where we discover multiple simultaneous degeneracies in the spectrum of a Kerr oscillator submitted to a squeezing drive, which models a quantum double well. What underlies these simultaneous degeneracies is the unusual destructive interference of tunnel paths in the classically forbidden region. Not only can these degeneracies be turned on-and-off on demand, but their number is tunable. Importantly, these degeneracies are robust as they are completely independent of the drive amplitude, revealing a hidden symmetry of our system. Our work, which we implement on a strongly driven superconducting circuit, indicates the circumstances by which the control of parametric processes via the drive frequency can provide a practical new tool for quantum technologies.

Bio:

Jaya hails from Bangalore, a city in the South of India. She moved to Kanpur, a city in the North of India, for her Bachelors studies and received a BS in Physics from Indian Institute of Technology Kanpur in 2016. Subsequently, she worked with Alexandre Blais at Université de Sherbrooke, where she worked on using optimal control theory for fast resonator reset. She started her PhD at Yale in the group of Michel Devoret in 2016. During her PhD, she developed tools to understand how the dynamics of a superconducting circuit is nontrivially modified when it is submitted to a microwave drive, and performed experiments to harvest this modification for quantum information processing. 

Outside of Physics, Jaya enjoys hiking, running, and spending time exploring nature. She is also trained in Carnatic music and Bharatanatyam and dabbles with these art forms.