Abstract: A system for the measurement of field properties includes a quantum system, a processor, and a memory. The quantum system includes a plurality of quantum sensors coupled to a field. Each sensor of the plurality of quantum sensors is located at a position in the field. The position depends on parameters. Each sensor of the plurality of quantum sensors is entangled. The memory includes instructions stored thereon, which, when executed by the processor, cause the quantum system to: access a signal of the quantum system; sense a plurality of interdependent a local field amplitudes corresponding to the plurality of quantum sensors by locally probing the field by each sensor of the plurality of quantum sensors; estimate a function of the parameters at a position x0, where x0 is a position without a quantum sensor of the plurality of quantum sensors; and estimate an amplitude of the field at the position x0 based on the estimated function of the parameters.

Abstract: A system for quantum state transfer and entanglement generation includes a quantum system including a plurality of qubits, a processor, and a memory. The memory includes instructions stored thereon, which, when executed by the processor, cause the quantum system to: access a signal of the quantum system; encode unknown coefficients in one qubit of the plurality of qubits; initialize each of the remaining qubits of the plurality of qubits in state |0; group the plurality of qubits into a plurality of subsystems; in each of the plurality of subsystems: encode quantum information into Greenberger-Horne-Zeilinger-like (GHZ-like) states using nearest-neighbor interactions; and apply a generalized controlled-phase gate between the plurality of subsystems to merge the GHZ-like states into an entangled state between of the plurality of subsystems.

Abstract: A quantum information processor (QIP) may include a plurality of quantum registers, each quantum register containing at least one nuclear spin and at least one localized electronic spin. At least some of the quantum registers may be coherently coupled to each other by a dark spin chain that includes a series of optically unaddressable spins. Each quantum register may be optically addressable, so that quantum information can be initialized and read out optically from each register, and moved from one register to another through the dark spin chain, though an adiabatic sequential swap or through free-fermion state transfer. A scalable architecture for the QIP may include an array of super-plaquettes, each super-plaquette including a lattice of individually optically addressable plaquettes coupled to each other through dark spin chains, and separately controllable by confined microwave fields so as to permit parallel operations.