Quantum logic via the exchange blockade in ultracold collisions

Area of Science:

• Quantum Computing
• Atomic Physics
• Quantum Information Science

Background:

• Nuclear spin can function as a quantum switch, controlling ultracold atom collisions.
• A novel mechanism termed "exchange blockade" leverages particle symmetry for quantum operations.
• This differs from traditional methods relying on direct qubit coupling.

Purpose of the Study:

• To investigate the implementation of an entangling gate using the exchange blockade mechanism.
• To model a proof-of-principle protocol for a $\sqrt{\text{SWAP}}$ gate with two atoms.
• To evaluate the gate's operational fidelity under varying conditions.

Main Methods:

• Utilizing a model system of two atoms with specific electronic and nuclear spin configurations.
• Employing optical tweezers for atom trapping.
• Simulating adiabatic evolution within a one-dimensional double Gaussian potential well.

Main Results:

• Demonstrated the feasibility of implementing a $\sqrt{\text{SWAP}}$ gate via exchange blockade.
• Calculated operational fidelities based on interaction strength, gate duration, and temperature.
• Identified key parameters influencing gate performance.

Conclusions:

• Exchange blockade offers a new pathway for quantum gate implementation in atomic systems.
• Symmetry-based mechanisms provide an alternative to direct qubit interactions.
• The study provides a foundation for developing robust quantum logic operations using nuclear spins.