Backaction Dephasing Induced by a Quantum Dot Detector

Yasuaki Masumoto, Fumitaka Suto, Michio Ikezawa +2 more

Toshihiro Kubo, 康弘 都倉

We derive an analytical expression for the backaction dephasing rate, which characterizes the disturbance induced by coupling with an environment containing a quantum dot detector (QDD). In this paper, we show in an explicit form that the charge noise induces backaction dephasing. In equilibrium, this backaction dephasing induced by the charge noise can be explained as a relaxation by an inelastic electron-electron scattering in Fermi-liquid theory. Unlike the quantum point contact, the backaction dephasing rate increases or decreases with the bias at low bias and finite-temperature condition. This behavior depends on the QDD energy level with respect to the Fermi energy and the asymmetry of the QDD coupling to the reservoirs. In the high bias voltage regime, the dephasing rate becomes insensitive to the bias because of the saturation of the charge noise.

Jorge Villavicencio, I. K. A. ROMERO MALDONADO, L. Debora Contreras-Pulido +2 more

David A. Ruiz‐Tijerina, E. Vernek, George Balster Martins +1 more

Will Grant, Sarath Sankar, Elena Cornick +9 more

Measurement perturbs a quantum system by coupling it to external degrees of freedom, but detector backaction depends on the physical mechanism of measurement itself. In solid-state devices, detectors driven far from equilibrium to enable faster measurements produce backaction that can often be understood as classical noise. However, a strong measurement can also induce backaction from quantum many-body correlations in the detector that are intrinsic to the measurement, even without shot noise. Here, we probe this near-equilibrium backaction through the effect of a quantum-dot charge sensor on tunnelling between a second quantum dot and its reservoirs. The measurement realizes the Anderson Orthogonality Catastrophe (AOC): electrons in the detector leads reorganize in response to an abrupt change in local scattering potential, suppressing resonant tunnelling while enabling inelastic processes that exchange energy with the detector. Changing the detector energy level tunes the AOC backaction from negligible to dominant in the tunnelling dynamics. More broadly, these results establish detector-induced many-body correlations as a controllable influence on quantum dynamics.

Uri Gavish, Yehoshua B. Levinson, Y. Imry