A flying Schrödinger cat in multipartite entangled states

Abstract

Schrödinger's cat originates from the famous thought experiment querying the counterintuitive quantum superposition of macroscopic objects. As a natural extension, several "cats" (quasi-classical objects) can be prepared into coherent quantum superposition states, which is known as multipartite cat states demonstrating quantum entanglement among macroscopically distinct objects. Here we present a highly scalable approach to deterministically create flying multipartite Schrödinger cat states, by reflecting coherent state photons from a microwave cavity containing a superconducting qubit. We perform full quantum state tomography on the cat states with up to four photonic modes and confirm the existence of quantum entanglement among them. We also witness the hybrid entanglement between discrete-variable states (the qubit) and continuous-variable states (the flying multipartite cat) through a joint quantum state tomography. Our work demonstrates an important experimental control method in the microwave region and provides an enabling step for implementing a series of quantum metrology and quantum information processing protocols based on cat states.

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• Entanglement-enhanced quantum metrology: from standard quantum limit to Heisenberg limit
• Fast Generation of GHZ-like States Using Collective-Spin XYZ Model
• Fault-tolerant quantum computation by hybrid qubits with bosonic cat-code and single photons
• Certifiable Lower Bounds of Wigner Negativity Volume and Non-Gaussian Entanglement with Conditional Displacement Gates
• An ultra-high gain single-photon transistor in the microwave regime
• Method to deterministically generate large-amplitude optical cat states
• Experimental Realization of Entangled Coherent States in Two-dimensional Harmonic Oscillators of a Trapped Ion
• Experimental preparation of generalized cat states for itinerant microwave photons
• Quantum repeater via entangled phase modulated multimode coherent states
• Non-Markovian environment induced Schrödinger cat state transfer in an optical Newton's cradle
• Seeding Gaussian boson samplers with single photons for enhanced state generation
• Certification of non-Gaussian Einstein-Podolsky-Rosen Steering
• Genuine Multipartite Entanglement induced by a Thermal Acoustic Reservoir
• Growing Schrödinger's cat states by local unitary time evolution of product states
• Entanglement generation via single-qubit rotations in a torn Hilbert space
• Flying-cat parity checks for quantum error correction
• Optimizing for an arbitrary Schrödinger cat state
• Two-Mode Bosonic State Tomography with Single-Shot Joint-Parity Measurement of a Trapped Ion
• Generation of bipartite mechanical cat state by performing projective Bell state measurement
• Reservoir-Engineered Mechanical Cat States with a Driven Qubit
• Single-shot conditional displacement gate between a trapped atom and traveling light
• Nonreciprocity enhanced Quantum Gyroscopes based on Surface Acoustic Waves
• Stabilization and Dissipative Information Transfer of a Superconducting Kerr-Cat Qubit
• Deterministic and Programmable Fusion for Scalable Generation of Photonic Graph States
• A no-go result on observing quantum superpositions