Advanced quantum technologies最新文献

The notion of synthetic dimensions in artificial systems has received considerable attention as it provides novel methods for exploring hypothetical topological matter as well as potential device applications. A superconducting qutrit-resonator chain is mapped into domain-divided Su-Schrieffer–Heeger (SSH) models in the synthetic dimension formed by product states of qutrits and Fock states, which renders single-excitation transfers to mimic particle transports in 1D potential array. Large-scale Greenberger–Horne–Zeilinger (GHZ) states can be generated in one-domain SSH model of synthetic dimension via the topological protected edge channel. Uniquely, a two-domain SSH model is constructed, and the wave function of the three topological protected states is analytically derived. It is shown that the effective coherent-tunneling adiabatic passage (CTAP) enables fast large-scale GHZ state can be generated via topological CTAP. Furthermore, four- and multi-domain SSH models are identified to generate large-scale GHZ states faster in larger sizes. Numerical results show that topologically generated large-scale GHZ states exhibit excellent robustness against inevitable variation in ideal hopping rates and losses of systems. The work opens up prospects for realizing fast large-scale GHZ states in multiple SSH models of synthetic dimension and for facilitating further applications of topological matter in quantum information processing.

An efficient multiparty semi-quantum private comparison protocol based on Bell states is proposed. The proposed protocol enables the comparison of private information equality among multiple classical participants with the assistance of two semi-honest third parties. Unlike previous protocols, the proposed protocol can be further extended to resist the collective-dephasing noise and the collective-rotation noise, respectively. The proposed protocol and its extensions do not require the classical participants to generate and send new quantum states to the third party, and these participants can compare two privacies within one round of comparison. In addition, the protocol performs better with a qubit efficiency up to 25%. The security analysis indicates that the protocol is resilient to various known quantum attacks. Furthermore, the feasibility of this protocol is confirmed by simulation results on the IBM quantum platform.

It is shown theoretically how to use the EPR (electron paramagnetic resonance) technique, using electron spins as qubits, coupled with each other by the exchange interaction, to set the configuration of n qubits (n = 1–4) at resonance, in conjunction with pulses, to construct the NOT (one qubit), CNOT (two qubits), CCNOT (three qubits), and CCCNOT (four qubits) Toffoli gates, which can be exploited to build a quantum computer. This is unique to EPR, wherein exchange-coupled electron spins are used. This is different from NMR (Nuclear Magnetic Resonance), which uses nuclear spins as qubits, that do not couple with each other by the exchange interaction.

Entanglement is one of the most vital resources in quantum computing. Particularly, in quantum game theory, entanglement holds significant importance since it defines the interactions and the information exchange between two or more players. In this research work, a new set of entanglement operators is introduced for N-player quantum games. This study explores how their application affects each player's behavior throughout the game. Furthermore, the entangling capabilities are tested and evaluated for a wide range of entanglement operator angles, by exploiting the Von Neumann entropy metric, both on a simulator and on a real IBM Quantum system. Their hardware efficiency, against state-of-the-art quantum games entanglement operators, is assessed in terms of circuit depths and fidelity, and showcases their great potential as multiplayer quantum games operators. Finally, three methods are compared for computing the players’ payoffs, regarding their scalability and efficiency. This study shows that in all payoff cases, the quantum game results, computed by the quantum hardware, are in accordance with the simulated ones.

In article number 2500253, Wenfeng Fan, Wei Quan, and co-workers report a novel in-situ magnetic noise compensation mechanism in a K-Rb-21Ne atomic comagnetometer, leveraging differential spin polarization of two alkali metals. This system decouples magnetic fields and inertial rotations in situ, enabling simultaneous measurement of both parameters and enhancing stability for precision spin-interaction studies.

In article number 2500202, Yun-Long Wang, Fei-Ran Wang, Ze-Hong Chang, and co-workers explored the feasibility of deploying high-dimensional orbital angular momentum (OAM) entanglement distribution through unmanned aerial vehicle platforms, and analyzed the influence of various system factors on entanglement fidelity through theoretical modeling. Furthermore, a high-dimensional subspace coding quantum key distribution protocol is introduced to maximally exploit the noise resistance of high-dimensional entanglement. Based on the mode-dependent characteristics of OAM, a protocol optimization scheme is developed specifically for the OAM degree of freedom. Simulation results demonstrate a significant enhancement in system performance and noise resistance.

Deterministic integration of droplet-etched GaAs quantum dots into micropillar cavities is demonstrated with 100% positioning yield. The collection efficiency for p-shell excitation is doubled by introducing charge stabilization using low-power above-band LED illumination. The deterministic integration method is then used to demonstrate suppression of radiation modes introduced by implementing cylindrical rings, and the fabricated devices emit high-purity single photons. More in article number 2500128, Battulga Munkhbat, Niels Gregersen, and co-workers.

In article number 2500147, Da Zhang, Ming-Xing Luo, and co-workers demonstrate a metropolitan quantum network enabled by continuous-variable entanglement, symbolized by jellyfish and octopuses as communication nodes. Such networks enable high-speed, secure communication. The research presents an all-optical verification to validate quantum links. The vibrant scene reflects the dynamic, interconnected nature of quantum information transfer, bridging theory and practical applications for next-gen internet.

The interplay between magnetism and superconductivity plays a crucial role in understanding unconventional superconductivity. Employing the proximity effect to realize superconductivity in ferromagnetic materials has generated widespread interest in achieving topological superconductivity and the novel Fulde−Ferrell−Larkin−Ovchinnikov state. Here, the proximity superconductivity is observed in a heterojunction of Fe₃GeTe₂ (FGT)/NbSe₂, in which FGT is a topological ferromagnetic material. The differential conductance of heterojunction shows three pairs of peaks, indicative of three superconducting phases (NbSe₂, proximate NbSe₂, and proximate FGT). The evolution of superconducting gaps adheres to Tinkham-Klapwijk theory and the superconducting gap in proximate FGT is estimated as ≈0.52 meV. Additionally, a non-reciprocal transport behavior is observed in the Josephson heterojunction of NbSe₂/FGT/NbSe₂. In this work, the interplay between ferromagnetism and superconductivity is explored systematically, providing a potential pathway for the realization of novel superconductivity.