Temporal modulation of the measurement rate provides a powerful mechanism for controlling open-system dynamics through measurement backaction. We demonstrate this mechanism in a minimal exactly solvable model of a continuously monitored quantum particle on a switching lattice. We derive exact analytical expressions for the long-time current under both periodic and stochastic switching, revealing a common slow-switching limit and identifying a measurement-induced crossover between Zeno- and anti-Zeno-dominated transport regimes that controls the direction of the current.Temporal modulation of the measurement rate provides a powerful mechanism for controlling open-system dynamics through measurement backaction. We demonstrate this mechanism in a minimal exactly solvable model of a continuously monitored quantum particle on a switching lattice. We derive exact analytical expressions for the long-time current under both periodic and stochastic switching, revealing a common slow-switching limit and identifying a measurement-induced crossover between Zeno- and anti-Zeno-dominated transport regimes that controls the direction of the current.

quant-pharXiv:2608.13109Aug 14, 20260 citations

Quantum critical temperature of a modulated oscillator

Vittorio Peano, Lingzhen Guo, Michael Marthaler +1 more

Bulletin of the American Physical SocietyMar 17, 20160 citations

Switching via quantum activation: A parametrically modulated oscillator

Michael Marthaler, M. I. Dykman

We study switching between period-two states of an underdamped quantum oscillator modulated at nearly twice its natural frequency. For all temperatures and parameter values switching occurs via quantum activation: it is determined by diffusion over oscillator quasienergy, provided the relaxation rate exceeds the rate of interstate tunneling. The diffusion has quantum origin and accompanies relaxation to the stable state. We find the semiclassical distribution over quasienergy. For $T=0$ , where the system has detailed balance, this distribution differs from the distribution for $T\ensuremath{\rightarrow}0$; the $T=0$ distribution is also destroyed by small dephasing of the oscillator. The characteristic quantum activation energy of switching displays a typical dependence on temperature and scaling behavior near the bifurcation point where period doubling occurs.We study switching between period-two states of an underdamped quantum oscillator modulated at nearly twice its natural frequency. For all temperatures and parameter values switching occurs via quantum activation: it is determined by diffusion over oscillator quasienergy, provided the relaxation rate exceeds the rate of interstate tunneling. The diffusion has quantum origin and accompanies relaxation to the stable state. We find the semiclassical distribution over quasienergy. For $T=0$, where the system has detailed balance, this distribution differs from the distribution for $T\ensuremath{\rightarrow}0$; the $T=0$ distribution is also destroyed by small dephasing of the oscillator. The characteristic quantum activation energy of switching displays a typical dependence on temperature and scaling behavior near the bifurcation point where period doubling occurs.

arXiv:cond-mat/0602288Physical Review AApr 20, 2006130 citations

Quantum Versus Classical Switching Dynamics of Driven Dissipative Kerr Resonators

Christian Kraglund Andersen, Archana Kamal, Nicholas A. Masluk +3 more

We report a first-principles study of the driven dissipative dynamics for Kerr oscillators in the mesoscopic regime. This regime is characterized by large Kerr nonlinearity, realized here using the nonlinear kinetic inductance of a large array of Josephson junctions. The experimentally measured nonlinear resonance lineshapes of the junction array modes show significant deviations from steady-state numerical predictions, and necessitate time-dependent numerical simulations indicative of strong measurement-induced dephasing in the system arising from the large cross-Kerr effect between array modes. Analytical and numerical calculations of switching rate corroborate this by showing the emergence of a slow time scale, which is much longer than the linear decay rate and is set by fluctuation-induced switching times in the bistable regime. Furthermore, our analysis shows that the usual quantum-activated escape treatment is inadequate for prediction of the switching rates at large frequency shifts caused by strong nonlinearities, necessitating a quantum treatment that utilizes the full system Liouvillian. Based on our analysis, we identify a universal crossover parameter that delineates the regimes of validity of semiclassical and quantum descriptions, respectively. Our work shows how dynamical switching effects in strongly nonlinear systems provide a platform to study quantum-to-classical transitions.We report a first-principles study of the driven dissipative dynamics for Kerr oscillators in the mesoscopic regime. This regime is characterized by large Kerr nonlinearity, realized here using the nonlinear kinetic inductance of a large array of Josephson junctions. The experimentally measured nonlinear resonance lineshapes of the junction array modes show significant deviations from steady-state numerical predictions, and necessitate time-dependent numerical simulations indicative of strong measurement-induced dephasing in the system arising from the large cross-Kerr effect between array modes. Analytical and numerical calculations of switching rate corroborate this by showing the emergence of a slow time scale, which is much longer than the linear decay rate and is set by fluctuation-induced switching times in the bistable regime. Furthermore, our analysis shows that the usual quantum-activated escape treatment is inadequate for prediction of the switching rates at large frequency shifts caused by strong nonlinearities, necessitating a quantum treatment that utilizes the full system Liouvillian. Based on our analysis, we identify a universal crossover parameter that delineates the regimes of validity of semiclassical and quantum descriptions, respectively. Our work shows how dynamical switching effects in strongly nonlinear systems provide a platform to study quantum-to-classical transitions.

arXiv:1906.10022Physical Review AppliedApr 7, 202031 citations

T=0

, where the system has detailed balance, this distribution differs from the distribution for $T\ensuremath{\rightarrow}0$; the

T=0

distribution is also destroyed by small dephasing of the oscillator. The characteristic quantum activation energy of switching displays a typical dependence on temperature and scaling behavior near the bifurcation point where period doubling occurs.