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Quantum lock-in detection (QLID) is crucial for extracting oscillating signals from noise, while quantum entanglement is vital to surpass the standard of quantum limit in precision measurement. Here, the authors experimentally realise entanglement-enhanced QLID using two trapped ions, achieving frequency measurement precision at the Heisenberg limit and demonstrating an improved inverse-quadratic temporal scaling.

A four-qubit processor of three phosphorus nuclear spins and an electron spin in silicon enables the implementation of a three-qubit Grover’s search algorithm with 95% fidelity. The implementation is based on an advanced multi-qubit gate with single-qubit gate fidelities above 99.9% and two-qubit gate fidelities above 99%.

We demonstrate high-fidelity entangling gates, universal quantum operations, and ancilla-based read-out for ultranarrow optical transitions of neutral atoms in a tweezer clock platform.

Future quantum computers will employ error correction to protect quantum data from decoherence and faulty hardware. Here, using a quantum processor with five superconducting qubits, the authors demonstrate how to protect one logical qubit from bitflip errors using multi-qubit, stabilizer measurements.

Using germanium quantum dots, a four-qubit processor capable of single-, two-, three-, and four-qubit gates, demonstrated by the creation of four-qubit Greenberger−Horne−Zeilinger states, is the largest yet realized with solid-state electron spins.

Perfect State Transfer is known to time-optimally connect distant nodes in a network. Here, the authors implement it on a chain of superconducting qubits and demonstrate that it also serves as a powerful tool for generating multi-qubit entanglement.

Qudit-based quantum devices can outperform qubit-based ones, but a programmable qudit-based quantum computing device is still missing. Here, the authors fill this gap using a programmable silicon photonic chip employing ququart-based encoding, showing the scaling advantages compared to the qubit counterpart.

Efficient protocols for comparing quantum states generated on different quantum computing platforms are becoming increasingly important. Zhu et al. demonstrate cross-platform verification using randomized measurements that allow for scaling to larger systems as compared to full quantum state tomography.

A programmable neutral-atom quantum computer based on a two-dimensional array of qubits led to the creation of 2–6-qubit Greenberger–Horne–Zeilinger states and showed the ability to execute quantum phase estimation and optimization algorithms.

Reaching a quantum advantage in metrology usually requires hard-to-prepare two-mode entangled states such as NOON states. Here, instead, the authors demonstrate single-mode phase estimation using Fock states superpositions in a superconducting qubit-oscillator system.

The ability to assemble weakly-interacting subsystems is a prerequisite for implementing quantum-information processing. In recent years, molecular nanomagnets have been proposed as suitable candidates for qubit encoding and manipulation, with antiferromagnetic Cr₇Ni rings of particular interest. It has now been shown that such rings can be chemically linked to each other and the coupling between their spins tuned through the choice of chemical linker.

Violation of the classical bound of the three-particle Mermin inequality by nine standard deviations is experimentally demonstrated by closing both the locality and freedom-of-choice loopholes; only the fair-sampling assumption is required. To achieve this, a light source for producing entangled multiphoton states and measurement technologies for precise timing and efficient detection were developed.

Exotic quantum states can be advantageous for sensing, but are very fragile, so that some form of quantum error correction is needed. Here, the authors show how approximate QEC helps overcoming decoherence due to noise when measuring the excitation population of a receiver mode in a superconducting circuit.

Quantum strategies can help to make parameter-estimation schemes more precise, but for noisy processes it is typically not known how large that improvement may be. Here, a universal quantum bound is derived for the error in the estimation of parameters that characterize dynamical processes.

A proof-of-principle study reports a complete photonic quantum computer architecture that can, once appropriate component performance is achieved, deliver a universal and fault-tolerant quantum computer.

It is hoped that simulations of molecules and materials will provide a near-term application of quantum computers. A study of the performance of error mitigation highlights the obstacles to scaling up these calculations to practically useful sizes.

A digitized approach to adiabatic quantum computing, combining the generality of the adiabatic algorithm with the universality of the digital method, is implemented using a superconducting circuit to find the ground states of arbitrary Hamiltonians.

Light could be used to carry quantum information in networks, but this requires methods to prepare and control individual photons. A superconducting circuit can controllably emit photons in either direction along a microwave waveguide.

A three-partite cluster state made of one semiconductor spin and two indistinguishable photons is generated from an InGaAs quantum dot embedded in a pillar microcavity. The three-partite entanglement rate is 0.53 MHz at the output of the device.

Fidelity benchmarking of an analogue quantum simulator reaches a high-entanglement regime where exact classical simulation of quantum systems becomes impractical, and enables a new method for evaluating the mixed-state entanglement of quantum devices.

A graph-theoretical programmable quantum photonic device composed of about 2,500 components is fabricated on a silicon substrate within a 12 mm × 15 mm footprint. It shows the generation, manipulation and certification of genuine multiphoton multidimensional entanglement, as well as the implementations of scattershot and Gaussian boson sampling.

High-order optical nonlinearities are a key tool in photonics and quantum optics, but their use is hindered by materials’ small intrinsic high-order susceptibility. Here, the authors show how to realize high-order nonlinear processes by combining intrinsic low-order ones in a microcavity.

In a quantum computer, the data carriers (or qubits) must be well isolated from their environment to avoid information leakage. At the same time they have to interact with one another to process information. A proposed platform based on spin qubits connected through arrays of nanoelectromechanical resonators should be able to reconcile these conflicting requirements.

By emulating a 2D hard-core Bose–Hubbard lattice using a controllable 4 × 4 array of superconducting qubits, volume-law entanglement scaling as well as area-law scaling at different locations in the energy spectrum are observed.

The universal control of six qubits in a ²⁸Si/SiGe quantum dot array is demonstrated, achieving Rabi oscillations for each qubit with visibilities of 93.5–98.0%, implying high readout and initialization fidelities.

Quantum computers, which harness the superposition and entanglement of physical states, hold great promise for the future. Here, the demonstration of a two-qubit superconducting processor and the implementation of quantum algorithms, represents an important step in quantum computing.

A controlled-controlled NOT, or Toffoli, gate is used to develop a fast, high-fidelity, three-qubit error correction protocol with the potential to correct arbitrary single-qubit errors.

Quantum entanglement is a key resource for technologies such as quantum communication and computation. A major question for solid-state quantum information processing is whether an engineered system can display the three-qubit entanglement necessary for quantum error correction. A positive answer to this question is now provided. A circuit quantum electrodynamics device has been used to demonstrate deterministic production of three-qubit entangled states and the first step of basic quantum error correction.

Manipulating the electrons trapped in quantum-dot pairs is one possible route to quantum computation. Translating this idea to three quantum dots would enable a whole host of extended functionality. Researchers now generate and manipulate coherent superpositions of quantum states using the spins across three electrical-gate-defined dots.

A network is frustrated when competing interactions between nodes prevent each bond from being satisfied. Frustration in quantum networks can lead to massively entangled ground states, as occurs in exotic materials such as quantum spin liquids and spin glasses. Here, a quantum simulation of a frustrated spin system is described, in which there are three trapped atomic ions whose interactions are controlled using optical forces.

Many-particle entangled states and entanglement between continuous properties are valuable resources for quantum information, but are notoriously difficult to generate. An experiment now entangles the energy and emission times of three photons, creating generalized Einstein–Podolsky–Rosen correlations.

Quantum measurements are subject to an uncertainty that is usually distributed equally between pairs of complementary properties (such as position and momentum). However, a technique known as 'squeezing' can be used to reduce the uncertainty of one desired property at the expense of increasing that of the other. Squeezing may have a critical role in high precision applications such as atomic clocks and optical communications. This paper demonstrates the ultimate squeezing limit for the polarization of a composite optical system.

Starting with wave-particle duality, experiments with light have played a major role in the development of quantum theory. Advances in photonic technologies allow for improved tests of quantum complementarity, delayed-choice and nonlocality.

Susceptibility to ferroptosis can be modulated by nitric oxide (NO^•) and NO synthase iNOS and through enrichment of activated M1 macrophages. NO inhibits the lipoxygenase 15-LOX that drives production of pro-ferroptotic lipids in macrophages.