Advanced quantum technologies最新文献

The application of quantum machine learning to large-scale high-resolution image datasets is not yet possible due to the limited number of qubits and relatively high level of noise in the current generation of quantum devices. In this work, this challenge is addressed by proposing a quantum transfer learning (QTL) architecture that integrates quantum variational circuits with a classical machine learning network pre-trained on ImageNet dataset. Through a systematic set of simulations over a variety of image datasets such as Ants & Bees, CIFAR-10, and Road Sign Detection, the superior performance of the QTL approach over classical and quantum machine learning without involving transfer learning is demonstrated. Furthermore, the adversarial robustness of QTL architecture with and without adversarial training is evaluated, confirming that our QTL method is adversarially robust against data manipulation attacks and outperforms classical methods.

The effect of pumping laser intensity uniformity (PLIU) on the operation of a hybrid optically pumped comagnetometer operating in the spin-exchange relaxation-free regime (SERF) regime is investigated in this paper. First, an analytical steady-state output model for the comagnetometer with two alkali-metal atoms and one noble-gas atom is presented. By varying the diameter of the pumping laser beam to control the PLIU, 3D distribution models of the electron spin and nuclear spin polarization under different PLIU conditions are obtained. In the experiment, the effects of PLIU on multi-parameter, low-frequency magnetic-noise suppression capability, and long-term stability of the SERF comagnetometer are studied. The results indicate that within a certain range, increasing the diameter of the pumping laser beam improves the polarization uniformity of the atomic ensemble and reduces the light shift of the comagnetometer. As a result, both the low-frequency magnetic noise suppression capability and the long-term stability of the system increase. However, further reduction of the pumping laser diameter leads to a reversal of the system performance metrics, suggesting the presence of a tipping point. The research presented in this article is critical for advancing the efficient polarization study and hyperpolarization of SERF comagnetometers.

This paper presents a quantum image secret sharing scheme based on designated multi-verifier signature. First, $�k$ share images are generated by a 2D hyperchaotic system incorporating sinusoidal mapping, Henon mapping, and Cubic mapping using the cascade modulation method. Quantum Arnold scrambling and diffusion are performed on the secret image. Subsequently, the concept of designated multi-verifier signature is introduced. In the secret image sharing phase, the pixel values of the share images are used to sign the secret image, and the signed secret image and $�k$ share images are sent to a trusted third party and $�k$ designated verifiers, respectively. In this scheme, no carrier images are required, and the share images held by the participants do not contain any information about the secret image. Finally, simulation experiments and security analysis are conducted on IBM Qiskit platform and Matlab software.

Entanglement witnesses are economical tools for the experimental detection of quantum entanglement. Quantum algorithms for entanglement detection have recently attracted considerable attention. Based on block encoding techniques and state preparation methods, the implementation of several types of entanglement witnesses using quantum circuits without quantum state tomography is proposed. Further, explicit quantum circuits for the block encoding of some special matrices are presented.

A theoretical scheme to enhance the sensitivity of a quantum fiber-optical gyroscope (QFOG) via a non-Gaussian-state probe based on quadrature measurements of the optical field is proposed. The non-Gaussian-state probe utilizes the product state comprising a photon-added coherent state (PACS) with photon excitations and a coherent state (CS). The sensitivity of the QFOG is studied and it is found that it can be significantly enhanced through increasing the photon excitations in the PACS probe. The influence of photon loss on the performance of QFOG is investigated and it is demonstrated that the PACS probe exhibits robust resistance to photon loss. Furthermore, the performance of the QFOG using the PACS probe against two Gaussian-state probes: the CS probe and the squeezed state (SS) probe is compared and it is indicated that the PACS probe offers a significant advantage in terms of sensitivity, regardless of photon loss, under the constraint condition of the same total number of input photons. Particularly, it is found that the sensitivity of the PACS probe can be three orders of magnitude higher than that of two Gaussian-state probes for certain values of the measured parameter. The capabilities of the non-Gaussian state probe in enhancing the sensitivity and resisting photon loss can have a wide-ranging impact on future high-performance QFOGs.

Superconducting diodes with nonreciprocal transport effect enable constructing novel logic devices, thereby laying the cornerstone of contemporary integrated circuits technology beyond Josephson junction-based circuits. Xiaofu Zhang, Lixing You, and co-workers designed and fabricated novel superconducting diodes based on the minimal superconducting electrical component – the superconducting nanowire –, which can rectify both square-wave and sine-wave signals without distortion (see article number 2300378). The superconducting nanowire diodes are irrespective of specific superconducting materials, and therefore promising for constructing low-dissipation superconducting integrated circuits for novel computation architectures.

A diamond quantum sensor, based on an ensemble of nitrogen-vacancy (NV) centers in diamond, is depicted being held by the author's hand. This sensor module is compact, highly magnetically sensitive, and stable. It was achieved by mounting a ¹²C-enriched chemical vapor deposition diamond, optics for high collection efficiency of NV fluorescence, and a balancing circuit to cancel out laser noise in the sensor module. This compact module is expected to be versatile across a broad spectrum of applications. For further information on the device and its applications, see article number 2300456 by Yuta Kainuma, Takayuki Iwasaki, and co-workers.

In article number 2400111, Zhu-Cheng Zhang, Yi-Ping Wang, and co-workers propose a scheme for implementing a one-dimensional cavity magnonics lattice that exhibits quantum magnon–photon Hall insulator behaviors. By adjusting corresponding parameters, different energy spectrum structures can be triggered, and the flipping of edge states can be observed, enabling multi-channel topological quantum state transmission.

Enhancing the capabilities of quantum computing relies heavily on harnessing the power of qudit-based high-dimensional quantum gates. In the study, single-qudit 4D $�X$, $�X^2$, and $�X^{†}$ gates tailored for a two-photon system in polarization states are presented. Furthermore, a two-qudit $��4�\times �4�$-dimensional controlled-not (CNOT) gate designed for a four-photon system is introduced. These high-dimensional gates can offer versatile and straightforward optical implementations, ensuring them to fulfill in a deterministic way. To facilitate these processes, an auxiliary system in the form of a $�\Lambda$-type atom residing in a cavity is employed. Remarkably, the auxiliary system retains its original state after the operation process ends, so it is not required to measure and plays a pivotal role in promoting effective interactions among distinct photons in its extended coherence time. Importantly, the in-depth analysis of the fidelities and efficiencies of these quantum gates showcase remarkable outcomes, affirming the superiority of the proposed protocols. Therefore, these high-dimensional gates not only amplify quantum parallelism, but also bolster the speed of quantum computations, fortify resilience against errors, and foster scalability for executing intricate quantum operations.