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Cavity-controlled Inhibition of Decoherence in Accelerated Quantum Detectors

Harkirat Singh Sahota, Shagun Kaushal, Kinjalk Lochan

Abstract

Vacuum fluctuations of quantum fields provide an unavoidable environment for any quantum system coupled to it. We study the interplay between boundary conditions and acceleration in determining decoherence of a two-level Unruh-DeWitt detector coupled to a scalar field in a cylindrical cavity. We show that the decoherence rate closely follows the emission profile, and exhibits {\it Purcell-like} enhancement for both inertial and uniformly accelerated detectors. The acceleration induces an effective smearing of the resonant density of states, diluting the resonance enhancement for large accelerations while replacing the inertial off-resonant decay with an oscillatory behavior for small accelerations. For moderate accelerations, this interplay between cavity-induced and acceleration-assisted effects results in an extended region of cavity parameters where decoherence is strongly suppressed, particularly in regimes where the inertial detector otherwise experience strong decoherence. Thus, contrary to naive expectations, the Unruh thermality in a suitably engineered cavity can enhance rather than degrade quantum coherence, providing a very uncharacteristic feature of quantum fields in non-inertial frames.

Cavity-controlled Inhibition of Decoherence in Accelerated Quantum Detectors

Abstract

Vacuum fluctuations of quantum fields provide an unavoidable environment for any quantum system coupled to it. We study the interplay between boundary conditions and acceleration in determining decoherence of a two-level Unruh-DeWitt detector coupled to a scalar field in a cylindrical cavity. We show that the decoherence rate closely follows the emission profile, and exhibits {\it Purcell-like} enhancement for both inertial and uniformly accelerated detectors. The acceleration induces an effective smearing of the resonant density of states, diluting the resonance enhancement for large accelerations while replacing the inertial off-resonant decay with an oscillatory behavior for small accelerations. For moderate accelerations, this interplay between cavity-induced and acceleration-assisted effects results in an extended region of cavity parameters where decoherence is strongly suppressed, particularly in regimes where the inertial detector otherwise experience strong decoherence. Thus, contrary to naive expectations, the Unruh thermality in a suitably engineered cavity can enhance rather than degrade quantum coherence, providing a very uncharacteristic feature of quantum fields in non-inertial frames.

Paper Structure

This paper contains 8 sections, 37 equations, 3 figures.

Table of Contents

  1. Introduction
  2. Decoherence of a monopole under Markovian evolution
  3. Inertial Decoherence in Cavity
  4. Acceleration and Decoherence
  5. Discussion
  6. Free-space limit
  7. Resonant decoherence for detector with small acceleration
  8. Fidelity and purity of a monopole under Markovian evolution

Figures (3)

  • Figure 1: Dimensionless decoherence rate $\mathcal{C}/\Omega$ of a uniformly accelerated atom inside a cylindrical cavity.
  • Figure 2: Near resonance behavior of the decoherence rate for $\epsilon=10^{-2}$ as a function of dimensionless energy gap near different resonance points.
  • Figure 3: At resonance versus near resonance behavior of dimensionless decoherence rate as a function of dimensionless energy gap at first resonance point.