Universal holonomic quantum gates over geometric spin qubits with polarised microwaves

Area of Science:

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

Background:

• A geometric phase, often overlooked, is shared between microwaves and electron spins.
• This phase enables universal holonomic gating for quantum bits (qubits).
• A geometric spin qubit is defined in the triplet spin qutrit subspace.

Purpose of the Study:

• To experimentally demonstrate nonadiabatic and non-abelian holonomic quantum gates.
• To utilize the geometric phase for manipulating qubits in nitrogen-vacancy centers.
• To showcase the universality of these gates for quantum information processing.

Main Methods:

• Experimental demonstration of holonomic quantum gates on electron and nitrogen nuclei spins.
• Manipulation of the geometric phase using polarized microwaves.
• Utilizing a nitrogen-vacancy center in diamond at room temperature and zero magnetic field.
• Implementing a two-qubit holonomic gate via electron-nucleus entanglement.

Main Results:

• Successful demonstration of nonadiabatic and non-abelian holonomic gates on a geometric spin qubit.
• Pure manipulation of the geometric phase achieved.
• Demonstration of a universal two-qubit holonomic gate.
• Electron-nucleus entanglement used to show gate universality.

Conclusions:

• Universal holonomic gates can be realized using the geometric phase in nitrogen-vacancy centers.
• These gates offer fast and fault-tolerant manipulation for quantum technologies.
• Potential applications include quantum repeaters and secure communication networks.