Classification of macroscopic quantum effects

Abstract

We review canonical experiments on systems that have pushed the boundary between the quantum and classical worlds towards much larger scales, and discuss their unique features that enable quantum coherence to survive. Because the types of systems differ so widely, we use a case by case approach to identifying the different parameters and criteria that capture their behaviour in a quantum mechanical framework. We find it helpful to categorise systems into three broad classes defined by mass, spatio-temporal coherence, and number of particles. The classes are not mutually exclusive and in fact the properties of some systems fit into several classes. We discuss experiments by turn, starting with interference of massive objects like macromolecules and micro-mechanical resonators, followed by self-interference of single particles in complex molecules, before examining the striking advances made with superconducting qubits. Finally, we propose a theoretical basis for quantifying the macroscopic features of a system to lay the ground for a more systematic comparison of the quantum properties in disparate systems.

6 pages

References in corpus (16)

• Coherent control of macroscopic quantum states in a single-Cooper-pair box
• Laser cooling of a nanomechanical oscillator into its quantum ground state
• Manipulating the Quantum State of an Electrical Circuit
• Observation of high coherence in Josephson junction qubits measured in a three-dimensional circuit QED architecture
• Quantum Entanglement of High Angular Momenta
• Macroscopicity of Mechanical Quantum Superposition States
• Macroscopic coherence of a single exciton state in a polydiacetylene organic quantum wire
• Crucial Role of Quantum Entanglement in Bulk Properties of Solids
• High Temperature Macroscopic Entanglement
• Quantification of Macroscopic Quantum Superpositions within Phase Space
• Stability of quantum states of finite macroscopic systems against classical noises, perturbations from environments, and local measurements
• Topological order in 1D Cluster state protected by symmetry
• Macroscopic optomechanics from displaced single-photon entanglement
• Macroscopic entanglement of many-magnon states
• Quantum instability and edge entanglement in a quasi-long-range order
• The size of macroscopic superposition states in flux qubits

Cited by in corpus (15)

• Quantum memories at finite temperature
• Macroscopic quantum states: measures, fragility and implementations
• A general framework for quantum macroscopicity in terms of coherence
• Quantum shape effects and novel thermodynamic behaviors at nanoscale
• Two-mode squeezed states as Schrodinger-cat-like states
• Quantum macroscopicity versus distillation of macroscopic superpositions
• Quantum Fluctuations in Mesoscopic Systems
• Is macroscopic entanglement a typical trait of many-particle quantum states?
• Optimal entanglement generation in optomechanical systems via Krotov control of covariance matrix dynamics
• Light-matter micro-macro entanglement
• Macroscopic superpositions as quantum ground states
• Long-lived mesoscopic entanglement between two damped infinite harmonic chains
• Assisted Macroscopic Quantumness
• Coherence Based Characterization of Macroscopic Quantumness
• Quantum Shape Effects