Experimental Realization of Nonunitary Multiqubit Operations.

Area of Science:

• Quantum Information Science
• Atomic, Molecular, and Optical Physics
• Quantum Computing

Background:

• Quantum computation relies on unitary operations, but nonunitary operations are crucial for tasks like error correction.
• Implementing irreversible quantum gates experimentally presents significant challenges.

Purpose of the Study:

• To introduce a novel experimental toolset for performing irreversible multiqubit operations.
• To demonstrate the feasibility of elementary nonunitary quantum gates (OR and NOR).

Main Methods:

• Utilized two trapped ^{40}Ca^{+} ions to encode logical information.
• Employed a cotrapped ^{88}Sr^{+} ion as a dissipation channel via sideband cooling to achieve irreversibility.
• Implemented and measured the success rates of OR and NOR gates.

Main Results:

• Achieved an 87% success rate for the OR gate.
• Achieved an 81% success rate for the NOR gate.
• Demonstrated a functional experimental setup for nonunitary quantum operations.

Conclusions:

• The developed toolset enables irreversible multiqubit operations on a quantum platform.
• This work provides a foundation for implementing more complex nonunitary operations.
• The methods are applicable to quantum error correction and quantum machine learning.