Generation of quantum entangled states of multiple groups of qubits distributed in multiple cavities

Abstract

Provided that cavities are initially in a Greenberger-Horne-Zeilinger (GHZ) entangled state, we show that GHZ states of N -group qubits distributed in N cavities can be created via a 3-step operation. The GHZ states of the N -group qubits are generated by using N -group qutrits placed in the N cavities. Here, "qutrit" refers to a three-level quantum system with the two lowest levels representing a qubit while the third level acting as an intermediate state necessary for the GHZ state creation. This proposal does not depend on the architecture of the cavity-based quantum network and the way for coupling the cavities. The operation time is independent of the number of qubits. The GHZ states are prepared deterministically because no measurement on the states of qutrits or cavities is needed. In addition, the third energy level of the qutrits during the entire operation is virtually excited and thus decoherence from higher energy levels is greatly suppressed. This proposal is quite general and can in principle be applied to create GHZ states of many qubits using different types of physical qutrits (e.g., atoms, quantum dots, NV centers, various superconducting qutrits, etc.) distributed in multiple cavities. As a specific example, we further discuss the experimental feasibility of preparing a GHZ state of four-group transmon qubits (each group consisting of three qubits) distributed in four one-dimensional transmission line resonators arranged in an array.

Single-step implementation of a hybrid controlled-not gate with one superconducting qubit simultaneously controlling multiple target cat-state qubits

“…In the past years, theoretical schemes for preparing multi-SC-qubit GHZ entangled states have been proposed [102][103][104][105][106][107], and the experimental production of GHZ entangled states with up to 18 SC qubits has been reported [12,18,19,[30][31][32][33][34]. The initial state of the whole system is thus given by…”

Nonclassical Effects Based on Husimi Distributions in Two Open Cavities Linked by an Optical Waveguide

“…Our physical interpretations of the HD-information and the Wehrl entropy-mixedness in qubit-cavity systems linked by a waveguide mode contribute to updating more potential applications for distributed quantum information processing that are based on realizing a multi-target-qubit unconventional geometric phase gate in a multi-cavity system [ 40 ], as well as entanglement stabilization protocols between two superconducting qubits that are coupled to distant cavities [ 41 ] and the architecture of the cavity-based quantum network [ 42 ]. It is found that certain coupling parameters of the exciton-cavity and the fiber-cavity interactions control the effects of the optical linear medium and the environment, which are major obstacles to the applications of the quantum information technology.…”

“…This is of importance to the conception of quantum networks based on distributed quantum nodes (qubits) for the storage and manipulation of quantum data [ 32 , 38 , 39 ]. Recent applications for qubit-cavity systems are based on realizing a multi-target-qubit unconventional geometric phase gate [ 40 ], entanglement stabilization protocols [ 41 ], and the network architecture [ 42 ]. We are also interested to analyze the generation and robustness of the phase space information and the mixedness in the cavity-fiber systems depending on the Husimi distribution and Wehrl entropy quantifiers.…”

High-fidelity quantum gates via optimizing short pulse sequences in three-level systems

“…This system allows quantum information to be encoded into two low-energy levels, with the transition being indirectly realized through a high-energy one. Some common three-level physical systems, such as nitrogen vacancy centers [24][25][26][27] and trapped ions [28][29][30], have been developed to reduce the unfavorable impact of decoherence on qubits.…”