Advanced quantum technologies最新文献

To improve the performance of room-temperature terahertz detectors, particularly regarding sensitivity and noise characteristics, an innovative detector incorporating a sawtooth array fabricated through femtosecond-laser direct writing is developed. This device integrates e localized surface plasma effect with the unique properties of a Weyl semimetal within a subwavelength structural framework. The application of a magnetic field combined with laser excitation further enhances carrier mobility, resulting in improved device performance and faster response times. At a frequency of 0.1 THz, the responsivity increases from 1.134 × 10⁵ to 1.192 × 10⁵ V/W, the noise-equivalent power decreases from 0.436 to 0.414 pW Hz^−1/2, and the response time is reduced from 210 to 49 ms. Additionally, terahertz time-domain spectroscopy reveals a distinct absorption feature at 0.1 THz, aligning with critical requirements for 6G communication systems. This design presents both a novel conceptual approach and a technological platform for the advancement of high-performance terahertz detection technologies.

A model of the Heisenberg spin chain quantum battery that is charged by noise is built, and the energy can be extracted. In a phase-flip noisy environment, it is found that there are sudden changes in steady-state energy and ergotropy with the variation of the nearest neighbor interaction strength on the $��x�y�$ plane. These sudden changes are associated with quantum phase transition (QPT), which has been shown through the crossover of the ground state energy level and the first excited state energy level, as well as the order parameters. In a thermal bath, the changes are investigated in steady-state energy and ergotropy with the variation of the nearest neighbor interaction strength on the $��x�y�$ plane. The components of Hamiltonian of the battery in the $�x$, $�y$, and $�z$ directions are used to explain the steady-state energy continuity at the QPT points. In addition, the effect of mean occupation number of the thermal bath on the steady-state energy and ergotropy is also considered. For the general Heisenberg spin chain and $�N$-qubit batteries, it is proved that the noise can also be used to charge the battery, and the ergotropy is non-zero.

The measurements of photoluminescence quantum yield are a standard characterization method of both traditional and novel fluorophores. Here, a detailed protocol is summarized for the measurements of quantum yield in colloidal samples of nanoparticles. Furthermore, based on a detailed discussion of the non-standard statistics of the experimental uncertainty connected with quantum yield measurements, a simple-to-apply method is put forward that allows proper sampling of the histogram of QY values. This histogram-sampling method serves as a robust reliability test of the measurement. Despite focusing on colloidal samples here, the histogram-sampling method itself and its implications are readily generalized to any other form of sample in QY measurements.

Noise remains one of the most significant challenges in the development of reliable and scalable quantum processors. While quantum error correction and mitigation techniques offer potential solutions, they are often limited by the substantial overhead required. To address this, tailored approaches that exploit specific hardware characteristics have emerged. In quantum computing architectures utilizing cat-qubits, the inherent exponential suppression of bit-flip errors can significantly reduce the qubit count needed for effective error correction. In this work, how the unique noise bias of cat-qubits can be harnessed to enhance error mitigation efficiency is explored. Specifically, it is demonstrated that the sampling cost associated with probabilistic error cancellation (PEC) methods can be exponentially reduced with the depth of the circuit when gates act on cat-qubits and preserve the noise bias. Similar results also hold for Clifford circuits and Pauli channels. The error mitigation scheme is benchmarked across various quantum machine learning circuits, showcasing its practical advantages for near-term applications on cat-qubit architectures.

A discrete ‘Quantum Memory Matrix’ lattice (central orange cell) symbolizes Planck-scale quantum memory units imprinting and retrieving local quantum fields. The circuit diagram below, featuring controlled-Ry, Ry, and CSWAP gates, illustrates the fully unitary QMM imprint–retrieval primitive that underpins enhanced error suppression and hybrid quantum-classical learning on NISQ devices. More in article number 2500262, Florian Neukart and co-workers.

The cover picture shows a controlled SWAP test quantum circuit with several state copies, and bitstrings (e.g., 0000, 1001, 1111) as measurement results. These bitstrings correspond to probabilities to simultaneously estimate traces of the 2nd to nth power traces of reduced density matrices via a single circuit, applied to entanglement measure computation. More in article number 2500376, Ming Li and co-workers.

A scheme is proposed to realize strong photon blockade (PB) effect in cavity magnomechanical system by incorporating a magnon parametric amplification (MPA). By analyzing the theoretical model of this system, it is found that the introduction of MPA not only increases additional transition pathways but also facilitates destructive interference between different transition paths, leading to a significantly enhanced unconventional photon blockade (UPB). This research demonstrates that PB is highly sensitive to phase and driving strength, and the optimized parameter relationships provide effective guidance for achieving quantum correlation. Furthermore, these conditions are closely related to the strength of the magnon-photon coupling, indicating the significant impact of the system's nonlinear characteristics on the photon–photon correlations. This work not only deepens the understanding of quantum interference in hybrid cavity systems but also provides a viable route toward realizing high-purity single-photon sources in magnomechanical platforms.

Symmetry breaking is commonly employed to optimize the functionalities of cavities, such as the single-wavelength resonance, directional output, or high quality-factor (Q). Due to the mutual influence and restriction of these performance metrics, it is a great challenge to realize high-Q multiple-wavelength resonances with each wavelength's emission being directional and distinguished. Here, a non-circular inner and circular outer (NICO) cavity is proposed, and dual-wavelength resonant modes with different in-plane emission directions for the two wavelengths are realized. More importantly, the Q of the two modes in the NICO cavity remains unchanged (100%) compared to the fully circular cavity. To gradually change the inner ellipse shape to the outer-circle shape, only the coordinates (not the refractive index) are transformed. This transformation makes the cavity easy to fabricate in the experiment. Both the band-gap confinement effect of the outer circle layers and the gradual change from the inner ellipse shape to the outer-circle shape significantly halt the Q-spoiling phenomena. Solutions of increasing refractive index differences and further breaking symmetry are provided to improve the Q factors (as high as 10¹³) and narrow the emission divergence angles (by approximately twice), as well as increase the splitting wavelengths (by ≈6 times).

Enhancing and controlling optomechanically induced higher-order sideband generation is essential to achieve high-sensitivity sensing. This study theoretically explores the amplified charge-dependent generation of optical second-order sidebands (OSS) within a cavity optomechanical system, facilitated by an atomic ensemble. Findings reveal that the presence of an atomic ensemble not only enhances OSS generation but also shows a more pronounced charge dependence in the output OSS spectrum compared to a single optomechanical cavity system. This enhancement inspires to explore charge measurements with higher sensitivity. The results demonstrate that the sensitivity of charge measurement can be elevated by over four orders of magnitude when additional atomic ensembles are incorporated. The proposed scheme presents a promising approach for charge measurement and holds significant potential for applications in quantum sensing.