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Readout of remote spins in quantum dot arrays is a challenge for future quantum computing architectures. Here, the authors implement electron cascade for spin readout on quantum dots far away from a charge sensor in a quadruple quantum dot device and discuss its applicability to large-scale arrays.

Quantum dot spin qubits in Si can be controlled using micromagnet-based electric-dipole spin resonance, but experiments have been limited to small 1D arrays. Here the authors address qubit control in 2D Si arrays, demonstrating low-frequency control of qubits in a 2 x 2 array using hopping gates.

Conveyor-mode spin shuttling using a two-tone travelling-wave potential demonstrates an order of magnitude better spin coherence than bucket-brigade shuttling, achieving spin shuttling over 10 μm in under 200 ns with 99.5% fidelity in an isotopically purified Si/SiGe heterostructure.

A cryogenic CMOS control chip operating at 3 K is used to demonstrate coherent control and simple algorithms on silicon qubits operating at 20 mK.

Singlet–triplet qubits implemented in a 2 × 4 germanium quantum dot array allow for a quantum circuit that generates and distributes entanglement across the array with a remote Bell state fidelity of 75(2)% between the first and last qubit.

When electrons are transported through a semiconductor quantum dot, they interact with nuclear spin in the host material. This interaction—often considered to be a nuisance—is now shown to provide a feedback mechanism that actively pulls the electron-spin Larmor frequency into resonance with that of an external microwave driving field.

The conventional approach to flipping electron spins in a semiconductor requires an external alternating field. It seems that the same job can be accomplished without external excitation of any kind.

Two electron spins occupying the outer dots in a linear array of three quantum dots experience a coherent superexchange interaction through the empty middle dot that acts as a quantum mediator.

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.

Gate-tunable superconducting quantum interference devices can be created in the two-dimensional superconductor formed at oxide interfaces.

Coupling semiconductor spin qubits over long distances using a superconducting resonator makes different quantum architectures possible. Now, the coherent swapping of quantum states has been observed between qubits coupled using this design.

Charge noise degrades the performance of spin qubits hindering scalability. Here the authors engineer the heterogeneous material stack in ²⁸Si/SiGe gate-defined quantum dots, to improve the scattering properties and to reduce charge noise.

The spin state of electrons in a double quantum dot in silicon is read in a single shot with 98% average fidelity within 6 μs by means of an on-chip superconducting resonator connected to two of the gates defining the double dot structure.

At low temperatures, a superconducting current that flows through a graphene layer sandwiched between two superconducting electrodes can be carried by either electrons or by holes, depending on the gate voltage that determines the charge density in the graphene layer. Interestingly, this finds that a finite supercurrent can flow even when the charge density is zero.

A spin-based quantum processor in silicon achieves single-qubit and two-qubit gate fidelities above 99.5% using gate-set tomography, exceeding the theoretical threshold required for fault-tolerant quantum computing.

Spin qubits in Si/SiGe quantum dots suffer from variability in the valley splitting which will hinder device scalability. Here, by using 3D atomic characterization, the authors explain this variability by random Si and Ge atomic fluctuations and propose a strategy to statistically enhance the valley splitting

In 1845, Faraday noted that the plane of polarization of light is rotated when a light beam travels through a material in a magnetic field. Now, Faraday rotation due to one single electron spin has been observed.

Although quantum physics underpins the behaviour of nanoscale objects, its role in nanoscience has been mostly limited to determining the static, equilibrium properties of small systems. This Review describes seminal developments and new directions for the explicit exploitation of quantum coherence in nanoscale systems, a research area termed quantum-coherent nanoscience.

Spin qubits are attractive for scalable quantum information, but integrating different classes of two-qubit logic has remained elusive. Here, the SWAP, CPHASE, and CNOT-class two-qubit gates are implemented in a silicon device operating even at temperatures above 1 K.