Resource-efficient analyzer of Bell and Greenberger-Horne-Zeilinger states of multiphoton systems

Abstract

We propose a resource-efficient error-rejecting entangled-state analyzer for polarization-encoded multiphoton systems. Our analyzer is based on two single-photon quantum-nondemolition detectors, where each of them is implemented with a four-level emitter (e.g., a quantum dot) coupled to a onedimensional system (such as a micropillar cavity or a photonic nanocrystal waveguide). The analyzer works in a passive way and can completely distinguish 2 n Greenberger-Horne-Zeilinger (GHZ) states of n photons without using any active operation or fast switching. The efficiency and fidelity of the GHZ-state analysis can, in principle, be close to unity, when an ideal single-photon scattering condition is fulfilled. For a nonideal scattering, which typically reduces the fidelity of a GHZstate analysis, we introduce a passively error-rejecting circuit to enable a near-perfect fidelity at the expense of a slight decrease of its efficiency. Furthermore, the protocol can be directly used to perform a two-photon Bell-state analysis. This passive, resource-efficient, and error-rejecting protocol can, therefore, be useful for practical quantum networks.

Phononic-waveguide-assisted steady-state entanglement of silicon-vacancy centers

“…Multiparticle entanglement has attracted great attention for its diverse applications in quantum metrology and quantum computing [1][2][3][4][5][6][7][8][9][10]. Efforts along this direction have lead to a plenty of proposals for generating entangled states with particles as many as possible [11][12][13], such as spin squeezing states [14][15][16] and GHZ states [17][18][19][20]. So far, multiparticle entanglement has been realized involving up to 20 qubits in trapped-ion systems [21], and 12 qubits in superconducting circuits [22].…”

Logic W‐state concentration with parity check

“…They also showed that this result has potential applications ranging from optical quantum information processing to QND photon‐number measurements 57 . In addition, some attractive PPC gates based on other nonlinear optical elements have also been proposed, such as those involving quantum‐dot spins in optical microcavities 58‐61 . For example, in 2019, Li et al proposed an error‐rejecting entangled‐state analyzer for polarization‐encoded multiphoton systems based on two single‐photon quantum‐nondemolition detectors, which can be constructed with quantum dots coupled to micropillar cavities 61 .…”

“…In addition, some attractive PPC gates based on other nonlinear optical elements have also been proposed, such as those involving quantum‐dot spins in optical microcavities 58‐61 . For example, in 2019, Li et al proposed an error‐rejecting entangled‐state analyzer for polarization‐encoded multiphoton systems based on two single‐photon quantum‐nondemolition detectors, which can be constructed with quantum dots coupled to micropillar cavities 61 . Based on above works, the PPC gate used in our protocol may be experimentally realized in the future.…”

Distinguishment of Greenberger–Horne–Zeilinger States in Rydberg Atoms via Noncyclic Geometric Quantum Computation

“…Next, we consider the distinguishment of N ‐qubit GHZ states. First of all, we define the N ‐qubit GHZ states as in 24]. For the N ‐qubit GHZ states, the simplest two are [ 16 ] in which the subscript of the N th qubit refers to the phase by the symbols ± (0 refers the phase +, while 1 refers the phase −).…”