Harmonic mixing in two coupled qubits: Quantum synchronization via ac drives

Abstract

Simulating a system of two driven coupled qubits, we show that the time-averaged probability to find one driven qubit in its ground or excited state can be controlled by an ac drive in the second qubit. Moreover, off-diagonal elements of the density matrix responsible for quantum coherence can also be controlled via driving the second qubit, i.e., quantum coherence can be enhanced by appropriate choice of the bi-harmonic signal. Such a dynamic synchronization of two differently driven qubits has an analogy with harmonic mixing of Brownian particles forced by two signals through a substrate. Nevertheless, the quantum synchronization in two qubits occurs due to multiplicative coupling of signals in the qubits rather than via a nonlinear harmonic mixing for a classical nano-particle.

Dirac fermion time-Floquet crystal: Manipulating Dirac points

“…In contrast, the nodes ofj x (θ) andj y (θ) are shifted by π/2, thus, resulting inj x (θ = π/2 + πn) = 0 andj y (θ = πn) = 0 for any α and k. Note that such an unprecedented level of the DC current control by varying parameters of the two frequency drive is remarkable and provides further analogy with the classical 24,25 , semi-classical 26 and quantum 27 harmonic mixing. Recently, it was shown 23 that a superposition of scalar potential barriers and time dependent laser fields can produce a resonant amplification of reflections of the Dirac fermions.…”

Noise-induced transitions in optomechanical synchronization

“…Further general insights into quantum synchronization were gained in a model system of one van-der-Pol oscillator coupled to an external drive [44] or two coupled van-der-Pol oscillators [45], which can serve as a rough approximation to an actual optomechanical system. A number of more recent works have explored quantum synchronization on the more conceptual level [46], as well as in various other physical systems, such as e.g.trapped atoms and ions [47][48][49][50], qubits [51][52][53], and superconducting devices [54]. The relation of synchronization and correlations in the quantum-to-classical transition was studied in a system of coupled cavities containing a non-linearity [55].…”

“…A number of more recent works have explored quantum synchronization on the more conceptual level [46], as well as in various other physical systems, such as e.g. trapped atoms and ions [47][48][49][50], qubits [51][52][53], and superconducting devices [54]. The relation of synchronization and correlations in the quantum-to-classical transition was studied in a system of coupled cavities containing a nonlinearity [55].…”

Dissipative dynamics in a tunable Rabi dimer with periodic harmonic driving

“…Varying the driving field strength is similar to tuning the qubit-photon coupling strength and the tunneling rate, leading to a more delocalized photon state [47]. As extensively studied by Savel'ev et al, manipulation of one qubit can be realized by applying an ac signal to an adjacent qubit coupled with it via interqubit interaction [46,[48][49][50]. We have a more sophisticated system with two photon modes and one phonon bath, but we still can indirectly alter the photon imbalance between the two resonators by changing the driving signal in one qubit coupled to its related resonator.…”