Quantum Interference Enabled Fredkin and SWAP Gates with Rydberg Atoms

Highly excited Rydberg atoms enable a wide range of applications in Quantum technology [1-18].  We present a direct protocol for implementing SWAP, √iSWAP, bSWAP, and controlled-SWAP (Fredkin) gates in Rydberg atom platforms by combining blockade physics with engineered quantum interference. Our scheme enables a four-photon mediated SWAP and conditionally suppresses it via control–target interactions, achieving controlled-SWAP in only three pulse steps. This direct realization drastically reduces circuit depth compared with decompositions requiring multiple CNOTs, while suppressing decoherence and crosstalk. Numerical simulations yield fidelities above 99% and robustness against Doppler shifts, laser-intensity noise, interatomic distance fluctuations, and long-range operations. Compared to anti-blockade proposals, our approach tolerates realistic temperatures (~150 µK) and laser fluctuations, eliminating the need for evaporative cooling. By enriching the native Rydberg gate set with exchange and controlled-SWAP operations, this protocol streamlines quantum algorithms and advances scalable, fault-tolerant quantum computing.

References:

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