One-step implementation of the genuine Fredkin gate in high-Q coupled three-cavity arrays

Abstract

We present two efficient methods for implementing the Fredkin gate with atoms separately trapped in an array of three high-Q coupled cavities. The first proposal is based on the resonant dynamics, which leads to a fast resonant interaction in a certain subspace while leaving others unchanged, and the second one utilizes a dispersive interaction such that the effective long-distance dipole-dipole interaction between two distributed target qubits is achieved by virtually excited process. Both schemes can achieve the standard form of the Fredkin gate in a single step without any subsequent single-qubit operation. The effects of decoherence on the performance of the gate are also analyzed in virtue of master equation, and the strictly numerical simulation reveals that the average fidelity of the quantum gate is high.

One-step implementation of a hybrid Fredkin gate with quantum memories and single superconducting qubit in circuit QED and its applications

“…We would like to mention that various schemes for achieving the three-qubit Fredkin gates have been previously suggested in [46][47][48][49][50][51][52], in which the two target qubits are encoded in two natural/artificial atoms [46][47][48][49][50][51] or photons [52]. Unlike the previous proposals, the target qubits of our gate are encoded in two superconducting resonators or NV ensembles which have the long coherence times.…”

“…In contrast to [51] where the target qubits are encoded by the discretevariable state, in our proposal the target qubits also can be encoded by the continuous-variable state. In addition, the proposals [46][47][48][49][50][51][52] require several operational steps and the microwave pulses, however, our proposal is much improved because our gate can be realized only using a single-step operation and no microwave pulses are needed.…”

Quantum information processing in cavities: A review

“…Fredkin gate [516][517][518], multi-qubit quantum phase gates [492,[519][520][521][522][523][524][525][526][527], etc. are proposed in cavity QED setup.…”

Classical Computation by Quantum Bits

“…Although these gates can be decomposed into 2-qubit gates and local unitaries [19], such implementations require at least five 2 qubit gates [20]. To achieve simplifications beyond this remit (including single pulse or "single-shot" implementations), nearly all schemes and actual implementations have variously used auxillary modes aside the relevant qubits, such as the cavity mode in hybrid qubit-resonator systems 2 [18,[21][22][23][24][25] or the motional modes in ion traps [17,26], or auxillary levels outside the space of qubits [25,27,28]. Where solely qubits have been used, either multiple pulses [29] or non-uniform and long-range couplings (departing from aim (b)) are generically present as in the NMR and other literature [30,31].…”