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The authors measure electric and magnetic noise, an important source of decoherence for quantum devices, on hole spin qubit devices in quantum wells in Ge/SiGe heterostructures, revealing a reduced charge noise on devices fabricated on Ge wafers.

Hole spin qubits in germanium are well suited for fast, electrically driven gates with high fidelity, but scaling to large qubit arrays remains challenging. Here the authors demonstrate a 10-spin qubit array with gate fidelities exceeding 99%, revealing mechanisms for uniform and scalable qubit control.

Hybrid superconductor-semiconductor devices offer a promising platform for topological superconductivity. Here, Ke and Moehle et al. create ballistic Josephson junctions in InSb quantum wells and use magnetic and electric fields to control their free energy landscape.

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.

Nuclear spin-free materials like ²⁸Si show promising electron spin coherence times, but qubit operation still suffers from low-frequency noise. Here the authors address this by applying open- and closed-loop feedback control methods including real-time Hamiltonian parameter estimation and dynamic voltage pulsing.

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.

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.

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

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.

The authors achieve gate-controlled proximitization of a quantum dot in a planar germanium heterostructure, an isotopically purifiable group IV material. A patterned Pt germanosilicide superconductor is introduced via a thermally activated reaction.

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.

Spin shuttling is a promising technique for establishing a quantum link between qubit registers and has been studied in several quantum dot qubit platforms. Here the authors realize coherent shuttling of a hole spin qubit in a minimal quantum dot chain in germanium despite strong spin-orbit coupling.

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.

An efficient control strategy is designed for quantum dot arrays, drawing inspiration from classical semiconductor technology. A two-dimensional array of 16 semiconductor quantum dots is operated using only a few shared control lines.

A coherent quantum link between distant quantum processors is desirable for scaling up of quantum computation. Noiri et al. demonstrate a strategy to link distant quantum processors in silicon, by implementing a shuttling-based two-qubit gate between spin qubits in a Si/SiGe triple quantum dot.

Single- and two-qubit gate fidelities above the fault-tolerance threshold for quantum computation are demonstrated in silicon quantum dots by fast electrical control using a micromagnet-induced gradient field and tunable coupling.

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.

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.

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.

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.

Germanium is a promising material to build quantum components for scalable quantum information processing. This Review examines progress in materials science and devices that has enabled key building blocks for germanium quantum technology, such as hole-spin qubits and superconductor–semiconductor hybrids.

The difficulty in obtaining a superconducting gap free of subgap states has hindered progress with hybrid superconductor-semiconductor devices in germanium. Here, this challenge is addressed by using a germanosilicide parent superconductor to contact high mobility planar germanium, facilitating scalable quantum information processing.