Abstract
We develop a new approach to understanding intrinsic mechanisms that cause the $T_1$-decay rate of a multi-level superconducting qubit to depend on the photonic population of a coupled, detuned cavity. Our method yields simple analytic expressions for both the coherently driven or thermally excited cases which are in good agreement with full master equation numerics, and also facilitates direct physical intuition. It also predicts several new phenomena. In particular, we find that in a wide range of settings, the cavity-qubit detuning controls whether a non-zero photonic population increases or decreases qubit Purcell decay. Our method combines insights from a Keldysh treatment of the system, and Lindblad perturbation theory.
Highlights
Circuit quantum electrodynamics systems based on superconducting circuits [1,2] are a leading platform for quantum information processing [3], and for explorations of basic quantum-optical and many-body phenomena [4,5]
A paradigmatic dissipative effect in cavity QED is Purcell decay [13], the modification of atomic decay by a cavity. Circuit quantum electrodynamics (cQED) systems motivate studying a modified version of this effect: What happens to Purcell decay when the cavity is populated with photons? This is of crucial relevance to understanding the experimentally-observed excess qubit decay during dispersive measurement [14,15] as well as the effect of background thermal radiation on qubit coherence
We introduce a theoretical approach to understanding Purcell decay in transmon-cavity systems in the presence of driving that complements and extends previous studies
Summary
Circuit quantum electrodynamics (cQED) systems based on superconducting circuits [1,2] are a leading platform for quantum information processing [3], and for explorations of basic quantum-optical and many-body phenomena [4,5]. CQED systems motivate studying a modified version of this effect: What happens to Purcell decay when the cavity is populated with photons (either by coherent driving or thermal noise)? We introduce a theoretical approach to understanding Purcell decay in transmon-cavity systems in the presence of driving that complements and extends previous studies. It provides compact analytic expressions that could be compared against experiment, and facilitates simple intuitive explanations It reveals several surprising effects not previously discussed. The unexpected interplay between a nonresonant dissipative process and a nonresonant Hamiltonian process yields the dominant contribution We discuss how this process would be completely missed if one resorted to standard secular approximations or considered a JC model instead of the transmon-cavity model analyzed here. It outlines an analytic approach that could be useful in studying a host of drivendissipative systems
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
