Abstract
We present an optical scheme for a SWAP test (controlled swap operation) that can determine whether the difference between two unknown states (photons) using cross-Kerr nonlinearities (XKNLs). The SWAP test, based on quantum fingerprinting, has been widely applied to various quantum information processing (QIP) schemes. Thus, for a reliable QIP scheme, it is important to implement a scheme for a SWAP test that is experimentally feasible. Here, we utilize linearly and nonlinearly optical (XKNLs) gates to design a scheme for a SWAP test. We also analyze the efficiency and the performance of nonlinearly optical gates in our scheme under the decoherence effect and exhibit a technique employing quantum bus beams and photon-number-resolving measurements to reduce the effect of photon loss and dephasing caused by the decoherence effect. Consequently, our scheme, which is designed using linearly optical devices and XKNLs (nonlinear optics), can feasibly operate the nearly deterministic SWAP test with high efficiency, in practice.
Highlights
The development of quantum technology has been explosive
Nondestructive SWAP test[17,22,23,24,25] has ancillary system for measurement. This SWAP test can be directly applicable from Fredkin gate, which performs the controlled swap operation
We present an optical scheme for the SWAP test, which is based on quantum fingerprinting[14], to certainly determine whether two unknown states are different using nonlinearly optical gates and a linearly optical gate (HOM gate)
Summary
We introduce the concept of a SWAP test (controlled swap operation) to determine whether two unknown states (|ψ〉 and |φ〉) are different. In optical fibers[56,57], photon loss (increasing error probability) in the probe beam and dephasing coherent parameters in the photon-probe system (decreasing the fidelity of the output state) occur because of the decoherence effect[26,27,32,52,53] when nonlinearly optical (path-parity and path-merging) gates are implemented in our SWAP test scheme, in practice. According to our analysis (the process model based on the master equation), we demonstrate that the utilization of the strong (increasing amNplitude) coherent state in nonlinearly optical gates (path-parity and path-merging gates in our SWAP test) will bring about high efficiency (small error probabilities) and reliable performance (robustness: high fidelities, and feasibility: weak XKNLs) with respect to the decoherence effect
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
