International Journal of Theoretical Physics最新文献

The precise position measurement of atoms using reflection and transmission beams of light is studied in this manuscript. It is reported that the transmission and reflection of probe light can be used to detect the localized position of atoms in one dimension which exhibit high resolution and varying number of peaks. Notably, sharp peaks of localization are reported in the transmission and reflection spectra, within the half-wavelength domain. Remarkably, the localized peaks undergo a shift from one half-wavelength domain to another when the sign of the phase in the standing wave field is altered. The theoretical results obtained for atom microscopy in the reflection and transmission spectra hold promising applications in advanced laser cooling technology.

In this paper, we consider positive oscillator-shaped well potential and set a Szilard-like quantum heat engine based on energy level degeneracy. By using position-dependent energy eigenvalues of the oscillator-shaped well, we compute extracted work and efficiency based on Stirling-like thermodynamical cycle. We obtain numerical results for physical quantities and discuss work and efficiency dependence of angular frequency, well width, and temperature.

The importance of reversible operations has been increasing day by day to overcome the drawbacks of irreversible computation. Quantum computers perform operations exponentially faster by taking advantage of reversible operations. Reversible operations play an essential role in developing energy and cost-efficient circuits. The efficiency of a quantum circuit is measured in terms of Quantum cost and Quantum depth. In this paper, we propose an optimization algorithm for Entanglement-based Quantum error correction, which plays a crucial role in various applications like quantum teleportation, secure communications, quantum key distribution, etc. We performed the experiments using Qiskit and RCViewer+ tools. Qiskit tool is used to run the quantum algorithms and measure the quantum depth; the RCViewer+ tool is used to measure the quantum cost. The proposed algorithm optimizes the quantum cost and depth compared to the existing approaches.

Quantum key agreement (QKA) is an advanced technique that allows multiple parties to share a secret key through cooperation. At present, most QKA protocols have the problems of weak anti-noise ability and low qubit efficiency. In this paper, two improved two-party QKA protocols are proposed using two sets of special logical qubits, which are immune to the collective noise. The main idea of these two protocols is that first, through the measurement correlation of the six-particle entangled states, the communication parties can fairly build a common key. Then, decoy logical qubits and delayed measurement technology are employed to prevent eavesdropping in quantum channels. Security analysis indicates that both protocols are unconditionally secure and capable of resisting internal and external attacks. In addition, compared with existing protocols, both protocols improve the efficiency because they transmit longer qubits.

Let (mathcal {OML}) denote the class of orthomodular lattices (OMLs, quantum logics). Let L be an OML and let B be a maximal Boolean subalgebra of L. Then B is called a block of L. In the algebraic investigation of OMLs a natural question is whether the blocks of a product (resp. ultraproduct) of OMLs are products (resp. ultraproducts) of the blocks of the respective “coordinate” OMLs. We first add to the study of this question as regards the products and the centres of the products (a special mention deserves the result that the centre of the ultraproduct is the ultraproduct of the centres of the respective OMLs). Then we pass to the analogous questions for ultraproducts where we present main results of this note. Though this question on the “regular” behaviour of blocks in ultraproducts remains open in general, we provide a positive partial solution. This contributes to the understanding of varieties important to quantum theories – to the varieties that contain both set-representable OMLs and projection OMLs. We consider an axiomatizable class of the OMLs, (mathcal {OML}_n), whose blocks uniformly intersect in finite sets of the maximal cardinality of (2^n). It is worth realizing within the connection to quantum logic theory that, for instance, the OMLs given by Greechie diagrams belong to (mathcal {OML}_2). The importance of the results is commented on in relation to the state space properties of OMLs.

We will prove how to create kinematical waves in spacetime. To this end we will combine the newfound technique to change locally the electromagnetic gauge in Minkowsky spacetimes by using ideal solenoids and the Aharonov-Bohm effect. The local kinematical states of spacetime represented by a new kind of local tetrad will be made to oscillate according to preestablished wave equations and we will show how to produce these effects from a mathematical point of view and from a technological point of view. Kinematical waves just to mention one possible application could be used for communication.

The limitation of traditional comparison protocols lies in the plaintext transmission of data or the sharing of encryption keys, which may lead to the risk of privacy disclosure. Compared with traditional comparison protocols, quantum private comparison (QPC) protocols utilize the characteristics of quantum computing and communication to provide higher security and privacy protection. Users in different domains often cannot communicate directly or find it difficult to choose the same trusted third party. Previous QPC protocols often had the same trusted or semi-honest third party and were unable to cope with private data comparison in cross-domain environments. We use product states of three-particle GHZ state and four-particle cluster state to realize QPC in cross-domain environment, and users only need to select the nodes they trust in their own domain. Then, we analyze the security of the protocol under various attacks, and show the security under channel node collusion attacks. Finally, we compare this protocol with other protocols to show that our protocol can be adapted to cross-domain environments.

In response to the emerging security challenges brought about by advances in quantum technology, traditional key agreement methods are encountering vulnerabilities. To address this issue, We propose a semi-quantum key agreement (SQKA) protocol that utilizes four different forms of the W state, a particle state with strong interparticle entanglement. Classical parties are pre-specified to perform distinct operations on various forms of W states, but these operations are completely random to other parties or potential attackers. Based on the sequence of measurement results transmitted by the quantum square and the pre-defined coding rules, the classical party can infer the operation performed by the other party to achieve identity authentication, and then publish the private key to generate the final key. The analysis of the protocol shows that it can effectively resist common inside and outside attacks, and has the advantage of being more efficient. In summary, by adopting SQKA protocol, we achieve a secure, fair and efficient key negotiation process, providing a feasible solution for cooperation between quantum and classical parties.

By viewing the cosmological parameter (Lambda ) as a dynamic variable, the thermodynamics of AdS black holes has been successfully extended to the case with inclusion of the thermodynamic pressure P. In this thermodynamic state space, although one has presented many interesting physical phenomenons, the Hawking radiation with thermodynamic pressure and volume remains to unknown. In this paper, we investigate the Hawking radiation as a tunneling process from the five-dimensional neutral Gauss-Bonnet AdS black holes, where the cosmological parameter and the Gauss-Bonnet coupling parameter are not constant but viewed as dynamical variable quantities of the black holes. The results show that the tunnelling rate of emitted particles is proportional to the ratio of the initial entropy and final entropy of black hole. The exact emission spectrum thus deviates from the pure thermal spectrum, which is the same as the case that the cosmological parameter is constant. This means that the tunneling rate of particles can be obtained in the extended phase space and the tunneling process does not depend on the thermodynamic state space. Thus naturally extending the Hawking radiation framework to the extended phase space, and it’s consistent with an underlying unitary theory in the extended phase space.

Following the works of Berest (2008), we compute explicitly Hadamard’s coefficients for two dimensional Schrödinger operators. For this, we use some specific generating functions and compute their relative Wronskians.