How to create entanglement is an important problem in quantum information processing. In this paper, we propose an experimental scheme to generate multi-photon W state using c-path gate and merging gate introduced in the former works. Compared with the other linear optical schemes, our scheme is deterministic without post-selection, and then there is no probabilistic problem and no limitation on the use of W state. Moreover, the required resources for generation grow linearly with the number of involved photons, which is obviously better than the polynomial growth with the traditional circuit-based quantum computation. This scheme is deterministic, suitability, and efficient, so it is feasible and suitable for large-scale quantum information processing.
How to create entanglement is an important problem in quantum information processing. In this paper, we propose an experimental scheme to generate multi-photon W state using c-path gate and merging gate introduced in the former works. Compared with the other linear optical schemes, our scheme is deterministic without post-selection, and then there is no probabilistic problem and no limitation on the use of W state. Moreover, the required resources for generation grow linearly with the number of involved photons, which is obviously better than the polynomial growth with the traditional circuit-based quantum computation. This scheme is deterministic, suitability, and efficient, so it is feasible and suitable for large-scale quantum information processing.
Quantum Dicke state belongs to the class of maximally entangled state. Due to its complicated entangled structure and robustness against decoherence, it is the important resource for the investigation of entanglement properties and the creation of quantum network. How to generate Dicke state and apply Dicke state in quantum communication protocol becomes a hot topic in the area of quantum information science. In this paper, we focus on the problem how to create arbitrary multi-photon Dicke state efficiently. The experimental generations and applications of four-photon and six-photon Dicke state had been reported in recent years. However, the generation is not scalable, that is it is difficult to generate Dicke state with more photons only using spontaneous parametric down-conversion and linear optical technology. If assisted with the weak cross-Kerr nonlinearity, it is possible to generate multi-photon Dicke state with some probability. However, it is still impossible to generate Dicke state with arbitrary coefficients, and the success probability decreases exponentially with the increasing of photon number. Here, we use three element gates called c-path gate, merging gate, entangler, which are introduced in former works, to design the generation of Dicke state. Firstly, the deterministic scheme of four-photon Dicke state generation is provided. After that, we modify the former W state generation scheme to be available for arbitrary coefficients W state generation. For the generation of arbitrary Dicke state, we decompose it to be a series of W state generations, with the help of c-path gates and merging gates. This scheme is deterministic and available for arbitrary coefficients. Especially, for some classes of Dicke states generation, the required resources are only polynomial growth with the increasing of photon number. All these features will make the investigation of multi-photon Dickes to be more convenient than the former schemes. In addition, our scheme is theoretically feasible with the current experimental technology.
Entanglement among multiple particles is a keystone for not only fundamental research on quantum information but also various practical quantum information applications. In particular, the W state has attracted a lot of attention due to the robustness against particle loss and the applications in multiparty quantum communication. However, it is challenging to generate a photonic W state with a large number of photons, since the N-photon W state requires superposition among N probability amplitudes. In this paper, we propose an efficient linear optical scheme to generate N-photon W states via quantum erasure. The success probability of our protocol polynomially decreases as the number of photons increases. We also discuss the experimental feasibility of our protocol and anticipate that one can efficiently generate tens of photonic W states with our scheme using currently available quantum photonics technologies.
How to implement multi-qubit gates is an important problem in quantum information processing. Based on cross phase modulation, we present an approach to realizing a family of multi-qubit gates that deterministically operate on single photons as the qubits. A general n-qubit unitary operation is a typical example of these gates. The approach greatly relax the requirement on the resources, such as the ancilla photons and coherent beams, as well as the number of operations on the qubits. The improvement in this framework may facilitate large scale quantum information processing.
Since linear-optical two-photon gates are inherently probabilistic, measurement-based implementations are particularly well suited for photonic platforms: a large highly-entangled photonic resource state, called a graph state, is consumed through measurements to perform a computation. The challenge is thus to produce these graph states. Several generation procedures, which use either interacting quantum emitters or efficient spin-photon interface, have been proposed to create these photonic graph states deterministically. Yet, these solutions are still out of reach experimentally since the state-of-the-art is the generation of a linear graph state. Here, we introduce near-deterministic solutions for the generation of graph states using the current quantum emitter capabilities. We propose hybridizing quantum-emitter-based graph state generation with all-photonic fusion gates to produce graph states of complex topology near-deterministically. Our results should pave the way towards the practical implementation of resource-efficient quantum information processing, including measurement-based quantum communication and quantum computing.
Abstract Herein, we present a scheme to prepare a hybrid-entangled W state that possesses the polarization states of two photons and the time-bin using cross-Kerr nonlinearities (XKNLs) and linearly optical devices. To maximize the merit of the entangled W state that can conserve entanglement against the loss of one qubit, we propose a method to prepare a two-photon hybrid-entangled W state correlated with degrees of freedom (polarization and the time-bin) via nonlinearly optical gates using XKNLs. In our scheme, the nonlinear gates consist of weak XKNLs, quantum bus beams, and photon-number-resolving measurements to realize the controlled-path gate and merging-path gate between two photons. To insert the time-bin information into photons, the time-bin encoder employs only linearly optical devices (delay lines and polarizing beam splitters). Subsequently, to evaluate the efficiency and experimental feasibility of our scheme for generating a two-photon hybrid-entangled W state, we analyzed the performance of nonlinear gates using XKNLs under the decoherence effect.
Based on two element operations, called controlled-path gate and entangler, the non-destructive multi-photon parity check could be deterministically realized. With these operations, the realization of loss-tolerant optical quantum computation, including the generation of parity states, the realization of single-particle operation and two-particle CNOT operation, could be very simple but deterministic and highly efficient. Moreover, the character of detected free of single photons in the computation, except of the parity-check, will make the requirement of single-photon resources much relax. Compared with the former linear optical schemes, this scheme with cross-phase modulation is simpler but deterministic, and more efficient but with less resource, which will make it more feasible and suitable for large-scale quantum computation.