Relaxation and decoherence in a resonantly driven qubit

Abstract

Relaxation and decoherence of a qubit coupled to environment and driven by a resonant ac field are investigated by analytically solving Bloch equation of the qubit. It is found that the decoherence of a driven qubit can be decomposed into intrinsic and field-dependent ones. The intrinsic decoherence time equals to the decoherence time of the qubit in free decay while the fielddependent decoherence time is identical with the relaxation time of the qubit in driven oscillation. Analytical expressions of the relaxation and decoherence times are derived and applied to study a microwave-driven SQUID flux qubit. The results are in excellent agreement with those obtained by numerically solving the master equation. The relations between the relaxation and decoherence times of a qubit in free decay and driven oscillation can be used to extract the decoherence and thus dephasing times of the qubit by measuring its population evolution in free decay and resonantly driven oscillation.

Analyses of the transmission of the disorder from a disturbed environment to a spin chain

“…These processes have a consequence on each component of the system, and could induce decoherence and relaxation. ( [1,2,3,4,5,6,7,8,9]). In order to explore this problem we consider the interesting example of a multipartite quantum system represented by a spin chain, i.e.…”

Decoherence, relaxation, and chaos in a kicked-spin ensemble

“…transitions from quantum state superpositions into incoherent classical mixtures of eigenstates. In order to study this process, spin baths [2][3][4][5][6][7][8][9] or quantum kicked tops [10][11][12][13] are interesting systems. Spin baths can be studied by NMR experiments and can be viewed as assemblies of qubits (a qubit is an unit of quantum information in quantum computing).…”

High‐order harmonic generation by static coherent states method in single‐electron atomic and molecular systems

“…Several numerical techniques have been developed for solving the TDSE, which are either based on the discretization on a grid or expansions into basis functions. The most recognized approaches are: discrete‐variable representation, 29–31 finite difference discretization, 32 and momentum‐space pseudospectral methods, 33 finite elements and B‐splines 34–36 time‐dependent configuration‐interaction 37–39 and multiconfiguration Hartree 40,41 . Although time‐dependent density functional theory has been used to approximate the quantum dynamics of some multi‐electron molecular systems, 42,43 a full understanding of the HHG process mandates full‐dimensional exact solution of the TDSE with coupled electron and nuclear dynamics beyond the Born–Oppenheimer approximation.…”

“…SCS method solves the 3D TDSE on the base of a static grid of coherent states (CS). CS have been implementing during the last two decades as an advantageous basis set for solving 3D TDSE for high dimensional quantum systems in the presence of an ultra‐short intense laser field 45,49–56 . One of their beneficial characteristics is that their grid can be generated randomly.…”