Decoherence and dissipation of a quantum harmonic oscillator coupled to two-level systems

Abstract

We derive and analyze the Born-Markov master equation for a quantum harmonic oscillator interacting with a bath of independent two-level systems. This hitherto virtually unexplored model plays a fundamental role as one of the four "canonical" system-environment models for decoherence and dissipation. To investigate the influence of further couplings of the environmental spins to a dissipative bath, we also derive the master equation for a harmonic oscillator interacting with a single spin coupled to a bosonic bath. Our models are experimentally motivated by quantum-electromechanical systems and micron-scale ion traps. Decoherence and dissipation rates are found to exhibit temperature dependencies significantly different from those in quantum Brownian motion. In particular, the systematic dissipation rate for the central oscillator decreases with increasing temperature and goes to zero at zero temperature, but there also exists a temperature-independent momentum-diffusion ͑heating͒ rate.

Temperature Dependence of Electric Field Noise above Gold Surfaces

“…Despite strong variation in the amplitudes S 0 , the turn-on temperatures T 0 are consistent through the data set. The finite zero-temperature intersect indicates either zero-temperature fluctuations, or a thermally activated process with activation energy less than 7 K [27].…”

From Zeno to anti-Zeno regime: Decoherence-control dependence on the quantum statistics of the bath

“…How does the bosonic or spin nature of the bath constituents influence the time scales of dephasing and its control? Recent works have addressed the differences between the spin and bosonic baths using second-order master equations [17,18]. Here we exactly analyze pure dephasing and its control, for spin and bosonic baths and contrast the two, showing the limitations of second-order master equations for each bath.…”

Quantum decoherence

“…A qubit linearly coupled to a collection of other qubits-also known as a spin-spin model -is often a good model of a two-level system (for example, a superconducting qubit) that interacts strongly with a lowtemperature environment [156,157]. The model of a harmonic oscillator interacting with a spin environment may be relevant to the description of decoherence and dissipation in quantum-nanomechanical systems and micron-scale ion traps [196]. For details on the theory of spin-environment models, see Refs.…”