Jeremy Estes: Continuous Monitoring of Rabi Oscillations in a Bose-Einstein Condensate

Continuous Monitoring of Rabi Oscillations in a Bose-Einstein Condensate

Abstract:

Fast, minimally disruptive measurements enable access to interactive quantum regimes, where weak or partial measurement and feedback coexist with unitary dynamics. A smooth handshake between quantum and classical hardware could allow protection of quantum information from decoherence, creation of entanglement-enhanced metrological devices, and studies of measurement- and feedback-induced states of matter. Various forms of weak measurement have emerged in the last two decades, using for example optical cavities or ancillae qubits for cold atoms, dispersively coupled transmission lines for superconducting systems, and photonic cavities for defect centers. Here I will present our experimental implementation of dispersive measurement techniques capable of continuously monitoring the evolving spin state of two-component Bose-Einstein condensates and ultracold ensembles near the standard quantum limit, without the use of cavities or ancillae. I will discuss results on the dynamics of Rabi oscillations subjected to variable-strength measurements, and the behavior of collective quantum states under the action of Ramsey-type pulse sequences in which dispersive measurements are interleaved with unitary drive pulses. Near-term upgrades and prospects for feedback applications will be presented at the end.