Controllable high-fidelity quantum state transfer and entanglement generation in circuit QED

Abstract

We propose a scheme to realize controllable quantum state transfer and entanglement generation among transmon qubits in the typical circuit QED setup based on adiabatic passage. Through designing the time-dependent driven pulses applied on the transmon qubits, we find that fast quantum sate transfer can be achieved between arbitrary two qubits and quantum entanglement among the qubits also can also be engineered. Furthermore, we numerically analyzed the influence of the decoherence on our scheme with the current experimental accessible systematical parameters. The result shows that our scheme is very robust against both the cavity decay and qubit relaxation, the fidelities of the state transfer and entanglement preparation process could be very high. In addition, our scheme is also shown to be insensitive to the inhomogeneous of qubit-resonator coupling strengths.

Fast and robust population transfer with a Josephson qutrit via shortcut to adiabaticity

“…After tracing out the environmental degrees of freedom 56 , we have the reduced density matrix ρ which is associated with , , and . For a weak coupling between the qutrit and the environment 57 , by taking the Born-Markov approximation, the dynamical evolution of ρ can be characterized by the Lindblad-type master equation 58 – 60 in which the first term governs the unitary evolution subject to a Λ-type driving, and the second term 47 contains the possible relaxations and dephasing effects caused by the noisy environment. Here γ ( kl ) and are the relaxation rate and dephasing rate regarding states and , respectively, and , with and .…”

High-fidelity State Transfer Between Leaky Quantum Memories

“…The reasoning is that in the second (first) half of the process, the excited population will largely be in S2 (S1), and therefore changes in the coupling for S1 (S2) will not substantially alter the state populations. It is worth noting that Xu et al [21] used a linear combination of Gaussian functions to construct the coupling profiles but also obtained an approximately flat shape for the driving field for Segment 1 (2) when the excited population was largely in Segment 2 (1). For t ≥ 0, we derive the following expressions (see the supplemental material):…”

Accelerating adiabatic protocols for entangling two qubits in circuit QED

“…Entanglement preparation via adiabatic methods in cQED was also studied in different frameworks and architectures; see, for instance, Refs. [24,[35][36][37].…”