Quantum Information Processing最新文献

In this paper, we propose an efficient scheme to fast generate three-particle Greenberger–Horne–Zeilinger (GHZ) state based on quantum Zeno dynamics and designing the evolution operators with Rydberg superatom. In the present scheme, the quantum information is encoded in the collective states of superatom which contains n individual four-level inverted Y-type Rydberg atoms, and the Rabi frequency can be fitted to a Gaussian function, which favors experimental feasibility. In addition, the influence of various decoherence factors such as atomic spontaneous emission, cavity decay and fiber leakage is also considered. The numerical simulation result shows that the present scheme is robust against decoherence and operational imperfection. At last, we generalize this scheme to the generation of N-particle GHZ state.

Due to the existence of decoherence, researchers are limited in controlling large-scale qubits, which also prevents the application of Shor’s factoring algorithm in the case of large-scale qubits for the time being. To reduce the number of qubits required when using Shor’s factoring algorithm, by using borrowed ancilla qubits and reducing the number of gates in the constant addition circuit, a new quantum circuit for Shor’s factoring algorithm is proposed. The designed circuit works on (2n+2) qubits, in practice is about 35% and 40% less than the best circuit of Takahashi et al. (Quantum Inf Comput 5(6):440–448, 2005) and Haner et al. (Quantum Inf Comput 17(7 &8):673–684, 2017) in terms of depth and size, respectively. Also, the designed circuit is completely general, and it does not depend on any property of the composite number to be factorized. Finally, we use Python with Qiskit to implement and simulate our circuit.

In the race for quantum computing supremacy, the key factor lies in maximizing the number of stable qubits by far, as each additional qubit doubles the computing power. Namely, it makes sense various ecosystems of organizations and developers gravitate toward these extraordinarily expensive supercomputers. Concurrently, the drive to democratize quantum computing has given rise to cloud-based operating systems built upon classical models. However, a growing demand forecast underscores the need for executing an infinite stream of near-real-time quantum tasks accessible via the cloud. This vacancy represents a potential boundary between quantum and classical operating systems. To address this, a refinement method called XIRAC-Q is introduced, which harnesses the principles of information theory for optimization. By maximizing the entropy toleration of the system, our approach enhances overall performance, particularly as the number of processes and tasks approaches infinity. Unlike the limited literature that has explored information theory principles solely for task priority alignment in classical computers, yielding limited advantage, our work integrates information theory and entropy in the design cycle of quantum operating system infrastructure. This paper highlights the novel advantages offered by the proposed paradigm, encompassing improved performance, scalability, and adaptability, which are thoroughly explained and explored.

In this work, we show the ability to restore states of quantum systems from evolution induced by quantum dynamical semigroups perturbed by covariant measures. Our procedure describes reconstruction of quantum states transmitted via quantum channels, and as a particular example, it can be applied to the reconstruction of photonic states transmitted via optical fibers. For this, the concept of perturbation by covariant operator-valued measure in a Banach space is introduced and integral representation of the perturbed semigroup is explicitly constructed. Various physically meaningful examples are provided. In particular, a model of the perturbed dynamics in the symmetric (boson) Fock space is developed as covariant measure for a semiflow of shifts and its perturbation in the symmetric Fock space, and its properties are investigated. Another example may correspond to the Koopman–von Neumann description of a classical oscillator with bounded phase space.

A recent paper (Quantum Info. Process 16.9, 2017) proposes a classical framework named Quantum Simulation Logic (QSL) capable of an efficient classical simulation of Deutsch–Jozsa and Simon algorithms. In this comment, we show instances of the Deutsch–Jozsa (DJ) and the Simon quantum algorithms that generate incorrect results with the QSL version, contradicting the proposal and the main results of the original paper.

In recent years, the development of graph states has opened a bright prospect for the generation of multipartite entangled states. However, due to the influences of noises in the surroundings, the obtained graph states may not be maximally entangled, which have been rarely explored previously. In this paper, we first consider how to generate one particular graph state which is named as the non-maximally entangled graph state. Next, we analyze the properties of the non-maximally entangled graph states and introduce two different kinds of graph states according to the entanglement of the non-maximally entangled graph states. Finally, we demonstrate how to teleport arbitrary unknown single-qubit state by using the non-maximally graph states. Compared with previous teleportation protocol, it demonstrates higher efficiency and lower operational complexity. We expect that our works can provide a theoretical instruction for the future study of the graph states.

Current work presents a new approach to quantum surface codes on compact surfaces with genus (g ge 2) using the identification of these surfaces with hyperbolic polygons and hyperbolic semi-regular tessellations. This method generalizes other contructions, and we show that this approach may give rise to codes with very good parameters. We present tables with several examples of these codes whose parameters had not been shown before.

This article proposes a benchmark testing set and evaluation system for quantum computers. Our tests do not focus on the topology of quantum computers or the specific implementation details of preparing quantum bits. Instead, we examine the overall performance of quantum computers from the perspective of users. Inspired by traditional computer benchmark tests such as SPECCPU2017, we integrate existing scalable quantum applications and algorithms to generate a testing set that covers algorithms such as search, machine learning, factorization, portfolio optimization, and entanglement state preparation, effectively simulating real workloads. By running the testing set, we can understand the performance of current quantum computers and generate a comprehensive score by combining our evaluation system, which consists of sub-scores of various backend features, including quantum gate error rate, entanglement between quantum bits, cross talk, and connectivity. These sub-scores are calculated based on the program features of the testing cases combined with their running results, where the program features are analyzed through the logical circuits of the testing cases. We incorporate Hellinger fidelity and polarization rescaling into each benchmark to calculate the fidelity of the running results. Through our evaluation system, researchers can be guided toward research directions and understand how far quantum computers are from solving practical problems.

The generation of entangled states in an optimized way is crucial to quantum information science and technology. Here, we propose an effective scheme for rapidly creating the entangled states between a transmon qubit and microwave photons by the technique of shortcuts to adiabaticity. An artificial atom of transmon circuit is coupled to a quantized resonator and a classical driving. The transmon-photon entanglement can be fast induced by inversely engineering the invariant-based Rabi drivings. Comparatively, the present scheme not only reduces the driving number but also employs the Rabi drivings with constant amplitudes. Furthermore, the operation fidelities can be enhanced due to a shorter duration time. Our work could offer an optimized avenue towards fast and robust information processing with superconducting qubits in a cavity.

It has been demonstrated that the critical point of the phase transition in scalar quantum field theory with a quartic interaction in one space dimension can be approximated via a Gaussian Effective Potential (GEP). We discuss how this critical point can be estimated using quantum hardware. Performing quantum computations with various lattice sizes, we obtain evidence of a transition from a symmetric to a symmetry-broken phase using both discrete- and continuous-variable quantum computation. The ten-site case is implemented on IBM quantum hardware using the Variational Quantum Eigensolver algorithm to minimize the GEP and identify lattice level crossings. These are extrapolated via simulations to find the continuum critical point.