Coherence, Asymmetry, and Quantum Macroscopicity

Abstract

We investigate a measure of quantum coherence and its extension to quantify quantum macroscopicity. The coherence measure can also quantify the asymmetry of a quantum state with respect to a given group transformation. We then show that a weighted sum of asymmetry in each mode can be applied as a measure of macroscopic coherence. To exclude the effects of microscopic superpositions, we suggest a method to introduce a cutoff to the weighted sum that will specify the macroscopic portion of the coherence. This cutoff may be interpreted as the fuzziness for a given measurement outcome. Based on the suggested measures, we investigate the quantum macroscopicity for particular concrete examples in N-partite spin systems.

12 pages, 3 figures

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Cited by in corpus (8)

• Relating out-of-time-order correlations to entanglement via multiple-quantum coherences
• Clock-work trade-off relation for coherence in quantum thermodynamics
• Family of coherence measures and duality between quantum coherence and path distinguishability
• Entanglement as the symmetric portion of correlated coherence
• Quadrature coherence scale driven fast decoherence of bosonic quantum field states
• Measuring the quadrature coherence scale on a cloud quantum computer
• Quantum asymmetry and noisy multi-mode interferometry
• Existence of maximally correlated states