Accelerating adiabatic protocols for entangling two qubits in circuit QED

Abstract

We introduce a method to speed up adiabatic protocols for creating entanglement between two qubits dispersively coupled to a transmission line, while keeping fidelities high and maintaining robustness to control errors. The method takes genuinely adiabatic sweeps, ranging from a simple Landau-Zener drive to boundary cancellation methods and local adiabatic drivings, and adds fast oscillations to speed up the protocol while canceling unwanted transitions. We compare our protocol with existing adiabatic methods in a state-of-the-art parameter range and show substantial gains. Numerical simulations emphasize that this strategy is efficient also beyond the rotating-wave approximation, and that the method is robust against random static biases in the control parameters and with respect to damping and decoherence effects.

Effect of Phase Errors on a Quantum Control Protocol Using Fast Oscillations

“…Let us now assume that the system is initially in an instantaneous eigenstate, say |ψ 0 = |j 0 . Then, using Equations (11), one can note that m 14it…”

“…This methodology has been theoretically exemplified in a precise circuit quantum electrodynamics (QED) experimental context in Ref. [11], where the experimental realizability is discussed in detail.…”

“…An interesting feature recognized in previous work [3,11] is that this scheme requires precise phase relations between oscillations in different Hamiltonian matrix elements, which may not be easily guaranteed experimentally. Nonetheless, it was also noticed that small phase offsets could interestingly lead to an unpredicted improvement of the method.…”

“…Our central result is Equation (26) highlighting the role of the phase biases on the efficiency of the protocol. In Section 5, it is then shown numerically that these mechanisms are present also in multilevel systems, by considering the case of a sped-up adiabatic protocol which produces entanglement between two qubits dispersively coupled to a resonator [11].…”

Selective Engineering for Preparing Entangled Steady States in Cavity QED Setup

“…In addition, the generation of a two-mode entangled states has been investigated by quantum reservoir engineering [6]. Other schemes based on the waveguide QED configuration are presented in [7][8][9][10][11][12].…”