Quantum-optical channels that output only classical states

Abstract

The Glauber-Sudarshan diagonal `weight' function provides a natural divide between the quantum-optical notion of classical and nonclassical states of continuous variables systems. Based on this demarcation, a channel is said to be nonclassicality breaking if it outputs only classical states for any input state. We focus on multimode bosonic Gaussian channels and classify those that are nonclassicality breaking by introducing a criterion that needs to be satisfied by the matrices representing these channels. The criterion can be interpreted as a nonclassicality benchmark for these channels since it quantifies the threshold noise at which there is a complete nonclassical to classical transition of the output states, i.e., it quantifies the robustness of the nonclassicality of the outputs of the channel against Gaussian noise. We then prove a striking `duality' between nonclassicality breaking and entanglement breaking bosonic Gaussian channels.

v3: close to published version

References in corpus (19)

• The Quantum Internet
• Experimental demonstration of quantum memory for light
• Quantum memory for squeezed light
• A computable measure of nonclassicality for light
• Experimental demonstration of three-color entanglement
• Continuous-variable quantum key distribution protocols over noisy channels
• Entanglement and purity of two-mode Gaussian states in noisy channels
• Multi-mode bosonic Gaussian channels
• Robustness of bipartite Gaussian entangled beams propagating in lossy channels
• Security of coherent state quantum cryptography in the presence of Gaussian noise
• Entanglement of Gaussian states using beam splitter
• Squeezing the limit: Quantum benchmarks for the teleportation and storage of squeezed states
• Limits on classical communication from quantum entropy power inequalities
• Gaussian optimizers and the additivity problem in quantum information theory
• The classical capacity of quantum thermal noise channels to within 1.45 bits
• Entanglement sensitivity to signal attenuation and amplification
• Phase-Covariant Quantum Benchmarks
• Quantum-entangled light from localized emitters
• The multi-mode quantum Entropy Power Inequality

Cited by in corpus (8)

• Quantum Resource Theories
• Operational resource theory of continuous-variable nonclassicality
• Non-Gaussian operations on bosonic modes of light: Photon-added Gaussian channels
• Coherence breaking channels and coherence sudden death
• Process output nonclassicality and nonclassicality depth of quantum-optical channels
• Divergence-free approach for obtaining decompositions of quantum-optical processes
• Fundamental limits on concentrating and preserving tensorized quantum resources
• Scaling maps of $s$-ordered quasiprobabilities are either nonpositive or completely positive