Continuous-variable geometric phase and its manipulation for quantum computation in a superconducting circuit

Abstract

Geometric phase, associated with holonomy transformation in quantum state space, is an important quantum-mechanical effect. Besides fundamental interest, this effect has practical applications, among which geometric quantum computation is a paradigm, where quantum logic operations are realized through geometric phase manipulation that has some intrinsic noise-resilient advantages and may enable simplified implementation of multiqubit gates compared to the dynamical approach. Here we report observation of a continuous-variable geometric phase and demonstrate a quantum gate protocol based on this phase in a superconducting circuit, where five qubits are controllably coupled to a resonator. Our geometric approach allows for one-step implementation of $n$-qubit controlled-phase gates, which represents a remarkable advantage compared to gate decomposition methods, where the number of required steps dramatically increases with $n$. Following this approach, we realize these gates with $n$ up to 4, verifying the high efficiency of this geometric manipulation for quantum computation.

12 pages, 10 figures

References in corpus (7)

• Observation of Berry's Phase in a Solid State Qubit
• Experimental Realization of Universal Geometric Quantum Gates with Solid-State Spins
• Realization of the quantum Toffoli gate with trapped ions
• Low-decoherence flux qubit
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