We study the optimization of the transport and transfer of neutral atoms between optical tweezers, both critical steps in the implementation of quantum computers and simulators. We analyze four experimentally relevant pulse shapes (piecewise linear, piecewise quadratic, minimum jerk, and a combination of linear and minimum jerk), and we also develop a protocol using shortcuts-to-adiabaticity (STA) methods to crucially incorporate the time-dependent effects of static traps. By computing a measure of the final transport error and two measures of the heating during transport, we show that our proposed STA protocol comprehensively outperforms all the experimentally inspired pulses. After further optimizing the pulse shapes, we find a lower bound on the protocol duration, compatible with the time at which the vibrational excitations exceed half of the states hosted by the moving tweezer. This lower bound is at least eight times faster than the one reported in recent experiments, which highlights the importance of including and optimizing the transfer from and to static traps, which may be the largest bottleneck to speed. Finally, our STA results demonstrate that a modulation in the depth of the moving tweezer designed to time-dependently counteract the effect of the static traps is key to reducing errors and reducing the pulse duration. To motivate the implementation of our STA pulses in future experiments, we provide a simple analytical approximation for the moving-tweezer position and depth controls.

We show that optomechanical pressure sensors with characterized density and thickness can achieve uncertainty as low as $1.1\mathrm{\%}$ via comparison with a secondary pressure standard. The agreement between the secondary standard and our optomechanical sensors is a necessary step toward using optomechanical devices as primary pressure sensors. Our silicon nitride and silicon carbide sensors are short-term and long-term stable, displaying Allan deviations compatible with better than $1\mathrm{\%}$ precision and baseline drift significantly lower than the secondary standard. Our measurements also yield the in situ thin-film density of our sensors with $1\mathrm{\%}$ total uncertainty or lower, aiding development of other optomechanical sensors. Our results demonstrate that optomechanical pressure sensors can achieve accuracy, precision, and drift sufficient to replace high-performance legacy pressure gauges.

When using unitary gate sequences, the growth in depth of many quantum circuits with output size poses significant obstacles to practical quantum computation. The quantum fan-out operation, which reduces the circuit depth of quantum algorithms such as the quantum Fourier transform and Shor’s algorithm, is an example that can be realized in constant depth independent of the output size. Here, we demonstrate a quantum fan-out gate with real-time feedforward on up to four output qubits using a superconducting quantum processor. By performing quantum state tomography on the output states, we benchmark our gate with input states spanning the entire Bloch sphere. We decompose the output-state error into a set of independently characterized error contributions. We extrapolate our constant-depth circuit to offer a scaling advantage compared to the unitary fan-out sequence beyond 25 output qubits with feedforward control, or beyond 17 output qubits if the classical feedforward latency is negligible. Our work highlights the potential of midcircuit measurements combined with real-time conditional operations to improve the efficiency of complex quantum algorithms.

Spatial filtering of optical fields has widespread applications, ranging from beam shaping to optical information processing; however, conventional spatial filters are bulky and alignment sensitive. Here, we present nonlocal non-Hermitian metasurfaces that can act as exceptionally effective optical spatial filters while being highly compact and insensitive to both lateral and longitudinal displacements. The design of these metasurfaces is based on a resonant waveguide grating in which radiative losses of the modes are tailored to realize a symmetry-protected bound state in the continuum in the middle of a non-Hermitian flat band. Using this design, we propose a compact spatial-filtering device operating over an angular range of approximately $1^{\circ }$ around normal incidence. In addition to being ultrathin and robust against translational misalignment, the proposed metasurfaces are easy to manufacture, which makes them an attractive alternative to conventional spatial filters, with the potential to become a widely used optical component.

Superconducting inductors with impedance surpassing the resistance quantum, i.e., superinductors, are important for quantum technologies because they enable the development of protected qubits, enhance coupling to systems with small electric dipole moments, and facilitate the study of phase-slip physics. We demonstrate superinductors with densely packed meandered traces of granular aluminum ($\mathrm{grAl}$) with inductances up to 4 µH, achieving impedances exceeding 100 kΩ in the 4–8 GHz range. Ring resonators made with $\mathrm{grAl}$ meandered superinductors exhibit quality factors on the order of ${10}^5$ in the single-photon regime, and low nonlinearity on the order of tens of hertz. Depending on the $\mathrm{grAl}$ resistivity, at 10 Hz, we measure frequency-noise spectral densities in the range of ${10}^2$–${10}^3\mathrm{Hz}/\sqrt{\mathrm{Hz}}$. In some devices, in the single-photon regime, we observe a positive Kerr coefficient of unknown origin. Using more complex fabrication, the devices could be released from the substrate, either freestanding or suspended on a membrane, thereby further improving their impedance by a factor of 3.

Quantum communication theory studies how quantum information is transmitted through quantum channels, with the transmission rate quantified by the quantum channel capacity. Quantum channels often exhibit rich and complex structures—such as nonadditivity—that make evaluating their capacities particularly challenging. In this work, we show that a type of quantum channel known as the antidegradable one-mode Gaussian channel—whose capacity is believed to be zero—can be “activated” to transmit quantum information with the assistance of quantum entanglement. Although the channel’s output alone cannot be used to retrieve the input signal, combining it with additional entanglement makes this possible. Beyond its theoretical implications, it can also be realized in practical systems. For example, in electro-optic systems used for quantum transduction in the two-mode squeezing interaction regime, the transduction channel is antidegradable. We demonstrate that this system can transmit microwave-optical quantum information with the assistance of entanglement with an ancillary mode. This results in a type of quantum transducer that exhibits positive quantum capacity over a wide parameter space.

We investigate loss mechanisms in hyperfluorescent organic light-emitting diodes (HF-OLEDs) with the emissive layer consisting of a host, a thermally activated delayed fluorescence (TADF) sensitizer, and a terminal emitter. We focus on understanding how the relative energy levels between the TADF sensitizer and terminal emitter impact device efficiency and roll-off through the formation and subsequent dissociation of an intermolecular state. Using a combined experimental and kinetic Monte Carlo (KMC) simulation-based approach, we analyzed HF-OLEDs incorporating either multiresonant (MR) or fluorescent (non-MR) terminal emitters. We find that selecting terminal emitters with ionization potential and electron affinity values that position the intermolecular state at least 150 meV above the singlet energy of the terminal emitter effectively suppresses the losses due to exciton dissociation. Furthermore, we show that using the MR emitter, which exhibits reverse intersystem crossing (RISC), significantly reduces residual triplet-related losses compared with the non-MR emitter. This further mitigates exciton dissociation losses, thereby improving the external quantum efficiency (EQE). These findings provide clear guidelines for selecting terminal emitters and optimizing energy level alignment to address intermolecular state-related loss pathways in HF-OLEDs.

We design phase-sensitive Rydberg-atom interferometry by implementing Floquet electromagnetically induced transparency (FEIT). The FEIT mixes the sidebands of a Rydberg state induced by a megahertz radio frequency (rf) field and recombines them into FEIT bands. The FEIT bands act as screens to present the interference between paths with different phases, which are transitions between the sidebands and excited states. This interferometry can measure the phase of a megahertz rf field without a local rf reference field. A phase reference is supplied to the atoms via a periodic electrical signal in the FEIT. We demonstrate that the megahertz rf phase can be resolved over the full $2\pi$ range with a theoretical accuracy of ${10}^{-4}$ rad. Moreover, the rf amplitude can also be resolved with higher accuracy than with the traditional EIT-based scheme.

We present and characterize a modular, open-source system to perform feedback control experiments on configurations of atoms and molecules in arrays of optical tweezers. The system features a modular computer architecture with a motherboard and peripheral cards, enabling continuous upgrades and flexible development while serving multiple applications. It supports efficient data transfer to and from graphics processing units (GPUs) using remote direct memory access, leveraging GPU efficiency in matrix multiplication and parallelism, while enabling direct data transfer between devices without involving the CPU. We first describe the architecture and workflow of the system, detailing its hardware components and software modules. We then evaluate the computational run time for preparing defect-free chains and grids of atoms using efficient implementations of atom-reconfiguration algorithms. Finally, we discuss timing bottlenecks and strategies to reduce latency. Beyond solving reconfiguration problems, the system can readily be used to implement adaptive and feedforward protocols, as well as digital quantum algorithms relying on particle displacement. Our results lay the groundwork for developing low-latency feedback control systems, benchmarking their performance, and advancing scalable quantum hardware.

Macroscopic quantum superpositions of massive objects are very interesting as they have several potential applications, ranging from the exploration of the interaction of gravity with quantum mechanics to quantum sensing. In this article, we propose two related schemes to prepare a spatial superposition of massive quantum oscillator systems with a high $Q$ factor via a superposition of magnetic forces. In the first method, we propose a large spatial superposition of a levitated spherical magnet generated via magnetic forces applied by adjacent flux qubits. We find that in this method the spatial superposition extent $\mathrm{\Delta }z$ is independent of the size of the particle. In the second method, we propose a large spatial superposition of a magnetically levitated flux qubit, generated via our driving the levitated qubit inductively. In both schemes, we show that ultralarge superpositions $\mathrm{\Delta }z/\delta z_{\mathrm{ZPM}}\sim {10}^4–{10}^6$ are possible, where $\delta z_{\mathrm{ZPM}}$ is the zero-point motional extent.

Superconducting devices have enabled breakthrough performance in quantum sensing and ultralow-power computing. Nevertheless, the need for a cryoelectronics platform that can interface superconductor electronics with complementary metal-oxide-semiconductor (CMOS) devices has become increasingly evident in many cutting-edge applications. In this work, we present a three-terminal micrometer-wide superconducting-wire-based cryotron switch (wTron), fabricated using photolithography, that can directly interface with CMOS electronics. The wTron features an output impedance exceeding $1\mathrm{k}\mathrm{\Omega }$ and exhibits reduced sensitivity to ambient magnetic noise, similar to its nanoscale predecessor, the nanocryotron. In addition, its micrometer-wide wires support switching currents in the milliamp range, making it well suited to driving current-hungry resistive loads and highly capacitive CMOS loads. We demonstrate this capability by using the wTron to drive room-temperature CMOS electronics, including a light-emitting diode and a metal-oxide-semiconductor field-effect transistor (MOSFET) with a gate capacitance of 500 pF. We then examine the optimal design parameters required for wTrons to drive CMOS loads, such as MOSFETs, high-electron mobility transistors, and electro-optic modulators. Furthermore, to demonstrate the foundry readiness of the wTron, we fabricate wTrons using MIT Lincoln Laboratory’s SFQ5ee superconducting process and characterize their switching behavior. Our work shows that the wTron will facilitate the interface between superconductor electronics and CMOS devices, thereby paving the way for the development of foundry-compatible cryoelectronic ecosystems to advance next-generation computing and quantum applications.

Quantum networks and distributed quantum computing rely on entanglement generation between photons and long-lived stationary qubits. For large-scale architectures, one of the most crucial parameters is the efficiency at which entanglement can be created and detected. Here, we maximize the efficiency for the detection of hybrid entanglement between a nuclear spin qubit in diamond with a photonic time-bin qubit. Our approach relies on the optimal implementation of a photonic qubit analyzer, for which we use a high-speed electro-optical deflector to direct photons deterministically along the optimal interferometer paths. This way, we eliminate all cases in which photons are randomly lost due to propagation in the wrong interferometer path. We use nitrogen-vacancy centers in diamond, for which we demonstrate nuclear spin–photon entanglement with a fidelity of 0.6 reducing the experimental acquisition time by a factor of 2. An extension to other spin–photon entanglement systems and higher-dimensional entanglement schemes is outlined.

The nonreciprocity created by dipolar coupling, electric currents, and Dzyaloshinskii-Moriya interactions is discussed in cases where the magnon propagation direction has a component parallel to the toroidal moment. A criterion for calculating the toroidal moments is established, addressing the issue of correct origin selection by considering compensated and uncompensated magnetization distributions. This criterion is then applied to various nonreciprocal magnetic systems, with the results of calculations consistent with those reported in the literature and predicting the existence of nonreciprocity in a more general manner. These results broaden the physical significance of the toroidal moment and facilitate the identification and estimation of nonreciprocity in magnonic systems. This work also clarifies the interrelations between different definitions of the toroidal moment for confined structures, where a surface term arising from surface-bound currents connects these definitions without the need for time averaging. Comparing these definitions of the toroidal moment applied to different magnetic textures demonstrates that they are always parallel but may differ in magnitude and sign. The discrepancy in the different definitions is deemed irrelevant since its direction, rather than its magnitude, primarily predicts the existence of magnon nonreciprocity.

State-of-the-art noisy-intermediate-scale quantum processors are currently implemented across a variety of hardware platforms, each with their own distinct gatesets. As such, circuit compilation should not only be aware of but also deeply connect to the native gateset and noise properties of each. Trapped-ion processors are one such platform that provides a gateset that can be continuously parameterized across both one- and two-qubit gates. Here we use the Quantum Scientific Computing Open User Testbed to study noise-aware compilations focused on continuously parameterized two-qubit $ZZ$ gates (based on the Mølmer-Sørensen interaction) using superstaq, a quantum software platform for hardware-aware circuit compiler optimizations. We discuss the realization of $ZZ$ gates with arbitrary angle on the all-to-all connected trapped-ion system. Then we discuss a variety of different compiler optimizations that innately target these $ZZ$ gates and their noise properties. These optimizations include moving from a restricted maximally entangling gateset to a continuously parameterized one, swap mirroring to further reduce the total entangling angle of the operations, focusing the heaviest $ZZ$ angle participation on the best-performing gate pairs, and circuit approximation to remove the least impactful $ZZ$ gates. We demonstrate these compilation approaches on the hardware with randomized quantum volume circuits, observing the potential to realize a larger quantum volume as a result of these optimizations. Using differing yet complementary analysis techniques, we observe the distinct improvements in system performance provided by these noise-aware compilations and study the role of stochastic and coherent error channels for each compilation choice.

We present a method for measuring the angle of arrival of 37-GHz radio-frequency (rf) radiation by mapping the standing waves generated in a rectangular glass vapor cell. These standing waves have regular and well-defined structure from which we can infer the angle and sign of the wavevector of the rf field. We map the field using spatially resolved light sheet spectroscopy of Rydberg states of rubidium atoms in the cell. Unlike traditional phased arrays, this detection scheme is compact, has an active area of nearly $4\pi$ steradians, and is sensitive to all rf polarizations. For in-plane measurements ($\varphi =0$), we demonstrate quantitative angle-of-arrival measurements with an uncertainty of the order of $1^{\circ }$ in an 11-s measurement, and for out-of-plane measurements (arbitrary $\theta ,\varphi$), we demonstrate angle-of-arrival detection with uncertainty of the order of several degrees.

Perpendicular magnetic anisotropy (PMA) and Dzyaloshinskii-Moriya interactions are key interactions in modern spintronics. These interactions are thought to be dominated by the oxidation of the $\mathrm{Co}/\mathrm{Al}$ interface in the archetypal platinum-cobalt-aluminum oxide system. However, in this study, we observe a double sign change in the anisotropy and about threefold variation in interfacial chiral interaction, influenced not only by the oxidation, but also by the metallic $\mathrm{Al}$ thickness. Contrary to previous assumptions about negligible spin-orbit effects at light metal interfaces, we observe not only strong PMA with fully oxidized $\mathrm{Al}$, decreasing and turning negative (in-plane) with less oxygen at the $\mathrm{Co}/\mathrm{Al}$ interface, but also that the magnetic anisotropy reverts to positive (out-of-plane) values at a fully metallic $\mathrm{Co}/\mathrm{Al}$ interface. These findings suggest modification in the $\mathrm{Co}$ d band via $\mathrm{Co}/\mathrm{Al}$ orbital hybridization, an effect supported by x-ray absorption spectroscopy and ab initio theory calculations, highlighting the key impact of strain on interfacial mechanisms at a fully metallic $\mathrm{Co}/\mathrm{Al}$ interface.

We develop a technique to measure small angular and lateral displacements of structured light beams. The technique relies on using high-order Hermite-Gaussian (HG) and Laguerre-Gaussian (LG) modes, which have well-defined symmetry under inversion. We show that the displacements of such fields lead to crosstalk with modes with opposite parity under inversion, which we measure optimally with an interferometric parity sorter. Using this technique, we achieve improvement factors of up to 41 in the signal-to-noise ratio using HG modes and 21 using LG modes with order up to 20, as compared to the fundamental Gaussian mode. Our results present a viable way of using structured light for metrology that does not demand quantum light or homodyne detection.

We investigate the superposition of coherent states, emphasizing quantum states with distinct Wigner phase-space features relevant to quantum information applications. In this study, we introduce generalized versions of the compass state, which display enhanced phase-space characteristics compared with the conventional compass state, typically a superposition of four coherent states. Our findings reveal that, unlike sub-Planckian structures and phase-space sensitivity of the compass state, these generalized states produce isotropic sub-Planckian structures and sensitivity to phase-space displacements. We demonstrate that these desirable phase-space characteristics are maintained in superpositions comprising at least six distinct coherent states. Furthermore, we show that increasing the number of coherent states in the superposition preserves these characteristics, provided the number remains even. We examine an optomechanical system capable of generating the proposed quantum states, resulting in optomechanical counterparts with nearly identical phase-space structures, thereby suggesting the feasibility of physically realizing these generalized compass states.