Abstract: A system for coupling a qubit to a register, wherein the system controls application of a protocol comprising a sequence of pulses synchronized with an RF field, the protocol further comprising a timing, a phase, and a duration of each of the pulses comprising a single qubit gate, a period and amplitude of the RF field, and a number of repeats of the sequence, so that application of the protocol controls a coherent spin exchange interaction between a register and a qubit having a zero magnetic dipole moment. The qubit comprises a first spin state and a second spin state both of which have a zero magnetic dipole moment; the register comprises multiple register spins having an energy level structure; and the register spins are indistinguishable so as to be configurable in basis states including a superposition state used for storing the quantum state of the qubit.

Abstract: Systems and methods for providing optical quantum communication networks based on rare-earth ion quantum bits (qubits) entrapped in solids are presented. According to one aspect a qubit is provided by an 171Yb3+ ion doped into a YVO crystal structure. A nanophotonic cavity fabricated in the doped crystal structure provides a zero-field energy level structure of the ion with optical transitions between ground and excited states at a wavelength longer than 980 nm. A subspace of the qubit is provided by two lower energy levels at the ground states separated by a microwave frequency of about 675 MHz. Addressing of the optical transitions is via first and second lasers and addressing of microwave transitions at the ground and excited states are via respective microwave sources. A single-shot readout sequence of the qubit based on two consecutive readout sequences on the optical transitions separated by a microwave pumping of the ground states is presented.

Abstract: Systems and methods for providing optical quantum communication networks based on rare-earth ion quantum bits (qubits) entrapped in solids are presented. According to one aspect a qubit is provided by an 171Yb3+ ion doped into a YVO crystal structure. A nanophotonic cavity fabricated in the doped crystal structure provides a zero-field energy level structure of the ion with optical transitions between ground and excited states at a wavelength longer than 980 nm. A subspace of the qubit is provided by two lower energy levels at the ground states separated by a microwave frequency of about 675 MHz. Addressing of the optical transitions is via first and second lasers and addressing of microwave transitions at the ground and excited states are via respective microwave sources. A single-shot readout sequence of the qubit based on two consecutive readout sequences on the optical transitions separated by a microwave pumping of the ground states is presented.