Multipartite Entanglement Generation and Contextuality Tests Using Nondestructive Three-Qubit Parity Measurements

Area of Science:

• Quantum Information Science
• Quantum Computing
• Solid-State Physics

Background:

• Nuclear spin qubits in diamond are promising for quantum information processing.
• Nondestructive quantum measurements are crucial for complex quantum state manipulation and error correction.
• Generating multipartite entanglement from mixed states is a key challenge in quantum science.

Purpose of the Study:

• To realize and apply nondestructive three-qubit parity measurements on nuclear spin qubits.
• To demonstrate the generation of genuine multipartite entangled states.
• To implement advanced quantum experiments for fundamental tests and quantum information protocols.

Main Methods:

• Utilized high-fidelity quantum logic to map three nuclear spin qubit parity onto an ancilla electron spin qubit.
• Employed single-shot nondestructive readout of the ancilla qubit.
• Applied electron spin echo to ensure outcome-independent evolution of nuclear spins.

Main Results:

• Successfully performed nondestructive three-qubit parity measurements on nuclear spin qubits.
• Demonstrated the generation of genuine multipartite entangled states from a maximally mixed state.
• Implemented a single-shot Greenberger-Horne-Zeilinger experiment and tested an eight-dimensional noncontextuality inequality.

Conclusions:

• The developed techniques are vital for fundamental quantum tests and quantum information protocols.
• Nondestructive parity measurements offer a powerful tool for creating and manipulating entangled states.
• This work advances the capabilities of nuclear spin qubits in diamond for quantum computing and sensing.