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Two-qubit operations exceeding 99% fidelity have been demonstrated by silicon devices made with standard semiconductor tooling in a 300-mm foundry environment.

Silicon-based spin qubits are promising candidates for a scalable quantum computer. Here the authors demonstrate the violation of Bell’s inequality in gate-defined quantum dots in silicon, marking a significant advancement that showcases the maturity of this platform.

Multielectron quantum dots offer a promising platform for high-performance spin qubits; however, previous demonstrations have been limited to single-qubit operation. Here, the authors report a universal gate set and two-qubit Bell state tomography in a high-occupancy double quantum dot in silicon.

A single electron spin in silicon is dressed by a microwave field to create a new qubit with tangible advantages for quantum computation and nanoscale research.

CMOS-based circuits can be integrated with silicon-based spin qubits and can be controlled at milli-kelvin temperatures, which can potentially help scale up these systems.

Global control of a qubits using a single microwave field is a promising strategy for scalable quantum computing. Here the authors demonstrate individual addressability vial local electrodes and two-qubit gates in an array of Si quantum dot spin qubits dressed by a global microwave field and driven on-resonance.

The coherent operation of individual ³¹P electron and nuclear spin qubits in a ²⁸Si substrate shows new benchmark decoherence times and provides essential information on the dechorence mechanism.

For solid-state qubits, the material environment hosts sources of errors that vary in time and space. This systematic analysis of errors affecting high-fidelity two-qubit gates in silicon can inform the design of large-scale quantum computers.

Diamond-based quantum computers could potentially operate at room temperature with optical interfacing, but their construction is challenging. Silicon carbide, used widely in electronics, may provide a solution. See Letter p.84

Initialization and operation of spin qubits in silicon above 1 K reach fidelities sufficient for fault-tolerant operations at these temperatures.

High-performance all-electrical control is a prerequisite for scalable silicon quantum computing. The switchable interaction between spins and orbital motion of electrons in silicon quantum dots now enables the electrical control of a spin qubit with high fidelity and speed, without the need for integrating a micromagnet.

A large nuclear spin has been successfully placed in a Schrödinger cat state, a superposition of its two most widely separated spin coherent states. This can be used as an error-correctable qubit.

Electron spins generated by phosphorus dopant atoms buried in silicon represent well-isolated quantum bits with long coherence times, but so far the control of such single electrons has been insufficient to use them in this way. These authors report single-shot, time-resolved readout of electron spins in silicon, achieved by coupling the donor atoms to a charge-sensing device called a single-electron transistor. This opens a path to the development of a new generation of quantum computing and spintronic devices in silicon.

A violation of Bell's inequality, which is a direct proof of entanglement, can be observed in the solid state using the electron and nuclear spins of a single phosphorus atom in silicon.

Donors spins in silicon are coherent, high-performance qubits, but scale-up has been challenging. Here the authors present the first experimental demonstration of exchange-based, entangling two qubit gates between electrons bound to ³¹P donors in Si.

Electrical detection and coherent manipulation of a single ³¹P nuclear spin qubit is reported; the high fidelities are promising for fault-tolerant nuclear-spin-based quantum computing using silicon.

The coherent manipulation of an individual electron spin qubit bound to a single phosphorus donor atom in natural silicon provides an excellent platform on which to build a scalable quantum computer.

Coherent quantum control of a single ¹²³Sb nucleus using electric fields produced within a silicon nanoelectronic device is demonstrated experimentally, validating a concept predicted theoretically in 1961.

CMOS technology can be used to miniaturize quantum-sensing technology based on nitrogen–vacancy centres in diamond.

Universal quantum logic operations with fidelity exceeding 99%, approaching the threshold of fault tolerance, are realized in a scalable silicon device comprising an electron and two phosphorus nuclei, and a fidelity of 92.5% is obtained for a three-qubit entangled state.

Qudits, higher-dimensional analogues of qubits, expand quantum state space for information processing using fewer physical units. Here the authors demonstrate control over a 16-dimensional Hilbert space, equivalent to four qubits, using combined electron-nuclear states of a single Sb donor atom in Si.

Understanding the microscopic variability of CMOS spin qubits is crucial for developing scalable quantum processors. Here the authors report a combined experimental and numerical study of the effect of interface roughness on variability of quantum dot spin qubits formed at the Si/SiO₂ interface.

Operating donor-based quantum computers in silicon is hindered by the dependence of inter-qubit coupling on the precise donor position. Here, the authors show controlled rotation operation on exchange-coupled electron spins in the weak-exchange regime, loosening the requirements on positioning precision.

Instead of using capacitively coupled charge sensors, which imply additional complexity in the device architecture, radiofrequency reflectometry on the gate defining the quantum dot can read out the spin state of a double quantum dot in a single shot.

Nuclear spins are excellent qubits, but long-range interactions are difficult to establish. Here, the authors couple a ²⁹Si nuclear spin to electrons in a lithographically defined quantum dot and show initialization, readout and entanglement with the electron spin. The ²⁹Si retains its coherence under electron transfer between quantum dots.