To catch and reverse a quantum jump mid-flight
Z.K. Minev, S.O. Mundhada, S. Shankar, P. Reinhold, R., Gutierrez-Jauregui, R.J. Schoelkopf, M. Mirrahimi, H.J. Carmichael, M.H., Devoret

TL;DR
This paper demonstrates that quantum jumps in a superconducting atom can be tracked in real-time, allowing for their reversal mid-flight, challenging the notion of their fundamental unpredictability and opening new avenues for quantum control.
Contribution
It provides the first experimental evidence that quantum jumps can be monitored continuously and reversed mid-flight, supporting quantum trajectory theory with real-time feedback.
Findings
Quantum jumps can be tracked during their evolution.
Real-time feedback allows reversing quantum jumps mid-flight.
Results align with theoretical predictions without adjustable parameters.
Abstract
Quantum physics was invented to account for two fundamental features of measurement results -- their discreetness and randomness. Emblematic of these features is Bohr's idea of quantum jumps between two discrete energy levels of an atom. Experimentally, quantum jumps were first observed in an atomic ion driven by a weak deterministic force while under strong continuous energy measurement. The times at which the discontinuous jump transitions occur are reputed to be fundamentally unpredictable. Can there be, despite the indeterminism of quantum physics, a possibility to know if a quantum jump is about to occur or not? Here, we answer this question affirmatively by experimentally demonstrating that the jump from the ground to an excited state of a superconducting artificial three-level atom can be tracked as it follows a predictable "flight," by monitoring the population of an auxiliary…
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Taxonomy
TopicsCold Atom Physics and Bose-Einstein Condensates · Quantum Information and Cryptography · Quantum Mechanics and Applications
