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Controllable two-qubit interactions are necessary to build a functional quantum computer. Here the authors demonstrate fast, coherent swapping of two spin states mediated by a long, multi-electron quantum dot that could act as a tunable coupler mediating interactions between multiple qubits.

Artificial nanostructures designed to simulate models of materials such as graphene provide insights into the material physics but can also have practical advantages. Du et al. create low-disorder artificial graphene devices, and present evidence of terahertz spin-exciton modes and large Coulomb interactions.

A device architecture based on indium arsenide–aluminium heterostructures with a gate-defined superconducting nanowire allows single-shot interferometric measurement of fermion parity and demonstrates an assignment error probability of 1%.

The entropy of a few-electron quantum system is measured for the first time by tracking the movement of charge in and out of the system. This could allow the unambiguous detection of Majorana fermions in solid state devices.

Nuclear spins in gallium arsenide produce noise at discrete frequencies, which can be notch-filtered efficiently to extend coherence times of electron spin qubits to nearly 1 ms.

Real-time adaptive control of a qubit has been demonstrated but limited to single-axis Hamiltonian estimation. Here the authors implement two-axis control of a singlet-triplet spin qubit with two fluctuating Hamiltonian parameters, resulting in improved quality of coherent oscillations.

Information transfer between distant qubits suffers from spurious interactions and disorder. Here, the authors report up to an order of magnitude enhancement in the quality factor of a swap operation of eigenstates in a quantum dot chain, by using a periodic driving protocol inspired by discrete time crystals.

Despite recent demonstrations of coherent spin-state transfer in arrays of spin qubits via exchange interaction, all-matter spin-state teleportation is still out of reach. Here the authors provide evidence for conditional teleportation of quantum-dot spin states, entanglement swapping, and gate teleportation.

The Bloch–Siegert shift—a strong-field phenomenon that implies a failure of the rotating-wave approximation—is observed in the polariton dispersion diagram of a two-dimensional electron gas system inside a high-Q terahertz photonic crystal cavity.

Topological kink modes are peculiar edge excitations that take place at ___domain boundaries of magnetic fields inside homogeneous materials. Here, the authors experimentally observe kink magnetoplasmons in a 2D electron gas using custom-shaped strong permanent magnets on top of a GaAs/AlGaAs heterojunction.

Previous demonstrations of spin state transfer in quantum dot chains relied on physical motion of electrons or sequences of SWAP operations. Here, the authors implement an alternative method based on adiabatic evolution, offering advantages in terms of implementation and robustness to noise and errors.

Transmission of single-spin and entangled quantum states without the physical displacement of electrons is demonstrated in a quadruple quantum dot array using the Heisenberg exchange interaction and coherent SWAP gates.