Advanced quantum technologies最新文献

The detection of laser-induced photo-currents in diamond is shown with about 100 fA resolution in the pico- to nanoampere range. A micro-electronic approach enables to work without using lock-in techniques. For that purpose, a commercially available and low-cost precision integrating amplifier is utilized on a home-built printed circuit board. This technique is applied to three different diamond samples with different defect concentrations. Two ultra-pure diamond samples with shallow implanted defects, predominantly nitrogen-vacancy (NV) centers and substitutional nitrogen (P1 centers), are investigated. The third sample is an electron-irradiated type Ib diamond with a much higher intrinsic defect concentration. For all samples, spatially resolved photo-current maps as well as laser power and bias voltage-dependent measurements are recorded. Furthermore, photo-currents are successfully recorded without an applied bias voltage. Finally, the technique is used to perform continuous wave photoelectric detection of magnetic resonances (PDMR) using NV centers. The presented approach paves the way for time-resolved photo-current measurements of individual defects and pulsed PDMR measurements without lock-in technology.

A master equation containing a nonlinear term that gives rise to disentanglement has been recently explored. Here, a modified version, which is applicable for indistinguishable particles, is proposed, and studied for both the Bose–Hubbard and the Fermi–Hubbard models. It is found for both Bosons and Fermions that disentanglement can give rise to quantum phase transitions.

This cover image illustrates the generation of microwave waveforms for qubit control by transforming superconducting single-flux-quantum (SFQ) pulses through a filtering network. The output microwave can be modulated by managing the condition of an SFQ pulse pair. Specifically, the reverse-polarity pulse-pair (RPPP) method enables maximum output amplitude and precise control over the initial phase of the microwave. This approach facilitates on-chip qubit control in a cryogenic environment, significantly reducing thermal noise and interconnecting cables, which is crucial for large-scale quantum computing. For further details see article number 2400001 by Hongxiang Shen, Yuxing He, Nobuyuki Yoshikawa, and co-workers.

Precise positioning of optical elements plays a key role in the performance of optical systems. While additive manufacturing techniques such as 3D printing enable the creation of entire complex micro-objectives in one step, thus rendering lens alignment unnecessary, certain applications require precise positional alignment of the printing process with respect to the substrate. For example, in order to efficiently couple quantum emitters to single-mode fibers, which is a crucial step in the development of real world quantum networks, precise alignment between the emitter, the coupling optics, and the single-mode fiber is of utmost importance. In this work, the positioning accuracy of a Photonics Professional GT (Nanoscribe GmbH) 3D printing machine is evaluated by using the integrated piezo stage to align to gold markers that is manufactured via e-beam lithography. By running a statistical analysis of 38 printing cycles, a mean positional error of only 80 nm is determined. Additionally, an entire system is 3D printed that can couple quantum emitters to optical single-mode fibers. Examining the focal spot of the 3D printed micro-optics, a positional accuracy of ≈ 1 µm in all three dimensions is found, as well as excellent quality of the focal spot.

In article number 2400043, Hai-Chao Li, Wei Xiong, and co-workers first propose to achieve nonreciprocal unconventional photon blockade with Kerr magnons. By tuning the direction of the biased magnetic field, the Kerr coefficient can be opposite, giving rise to nonreciprocity. With such a nonreciprocal nonlinearity, direction-dependent unconventional photon blockade, destructively interfering between two transition paths, can be realized in single- and two-sphere cavity–magnon systems. By tuning magnon–photon coupling, reciprocal and nonreciprocal photon blockade can be arbitrarily switched for two-sphere setup. This study offers a potential platform for investigating nonreciprocal photon blockade effect with Kerr magnons.

In the realm of fundamental quantum science and technologies, non-classical states of light, such as single-photon Fock states, are widely studied. However, current standards and metrological procedures are not optimized for low light levels. Progress in this crucial scientific domain depends on innovative metrology approaches, utilizing reliable devices based on quantum effects. A new generation of molecule-based single-photon sources is presented, combining their integration in a polymeric micro-lens with pulsed excitation schemes, thereby realizing suitable resources in quantum radiometry. The strategy enhances the efficiency of generated single photon pulses and improves stability, providing a portable source at 784.7 nm that maintains consistent performance even through a cooling and heating cycle. The calibration of a single-photon avalanche detector is demonstrated using light sources with different photon statistics, and the advantages of the single-molecule device are discussed. A relative uncertainty on the intrinsic detection efficiency well below 1% is attained, representing a new benchmark in the field.

In this paper, on the design process of a multiparty quantum key agreement protocol within a $�d$-dimensional Hilbert space is elaborated upon. A circular-type multiparty quantum key agreement protocol based on the generalized Bell state is introduced. To enhance security against external attacks, $�n$ decoy states into the transmission process is incorporated. Transmission sequences of the generalized Bell state and decoy states are passed between participants. The participants then encode their secret information into the corresponding particles. Ultimately, all participants are able to derive the same key. In addition, a combination of $�d$-dimensional Pauli operators is utilized, making the proposed protocol feasible with current technology. Analysis and protection against intercept-resend attack, entangle-measure attack and dishonest participants attacks, demonstrating the feasibility of the protocol in a $�d$-dimensional Hilbert space. The protocol has certain advantages over other protocols in terms of a comprehensive consideration of security and efficiency.

Platinum-group transition-metal dichalcogenides have emerged as a subject of considerable interest in condensed matter physics because of their remarkable topological properties and unconventional superconducting behavior. In this study, the synthesis and superconducting characteristics of a layered chalcogenide RhSeTe crystallized in the 1$�T$-structure, known for hosting materials with nontrivial topology characteristics are reported. RhSeTe exhibits type-II superconductivity, with a superconducting transition temperature of 4.72 K and a high upper critical field  4.06(7) T.

The nonreciprocal property of quantum systems is crucial for chiral quantum networks. In this study, a phase-controlled scheme is proposed to enhance the nonreciprocal quantum entanglement and optical transmission in a cavity optomechanical system by introducing a phase-dependent unidirectional coupling between two whispering-gallery-mode (WGM) resonators. The Sagnac effect induced by the spinning resonator generates nonreciprocity, while the interference effect between direct evanescent coupling and indirect phase-dependent unidirectional coupling significantly enhances entanglement under the anti-Stokes sideband. For specific coupling phases, ideal nonreciprocity can be achieved in both entanglement and transmission. The proposed phase-controlled nonreciprocity presented offers an effective strategy for constructing a unidirectional quantum channel and implementing an optical diode in chiral quantum networks, thereby opening up new possibilities for applications in quantum technologies.