Experimental Realization of Direct Entangling Gates between Dual-Type Qubits

Area of Science:

• Quantum Information Science
• Atomic Physics
• Quantum Computation

Background:

• Dual-type qubits are crucial for mitigating crosstalk errors in large-scale ion trap quantum computers.
• Efficiently controlling and entangling these qubits is essential for advancing quantum computation.

Purpose of the Study:

• To demonstrate a direct entangling gate between dual-type qubits encoded in different hyperfine manifolds.
• To assess the fidelity of this gate and compare it with same-type qubit gates.

Main Methods:

• Utilized a single 532 nm laser system to drive Raman transitions for entangling S-D ion pairs in ^{137}Ba^{+} ions.
• Implemented a Molmer-Sorensen gate to create entanglement between dual-type qubits.

Main Results:

• Achieved a high Bell state fidelity of 96.3(4)% for the dual-type Molmer-Sorensen gate.
• The fidelity is comparable to that obtained for same-type (S-S or D-D) qubit gates.
• The scheme requires only a single laser system, indicating hardware economy.

Conclusions:

• This direct entangling gate technique effectively suppresses crosstalk errors in dual-type qubits.
• It reduces the overhead associated with qubit type conversions in quantum circuits.
• The method has broad applicability in quantum error correction and ion-photon quantum networks.