Efficient creation of spin squeezed ground states

Gael Reinaudi, Alice Sinatra, Aurélien Dantan +1 more

We present a realistic model for transferring the squeezing or the entanglement of optical field modes to the collective ground state nuclear spin of 3He using metastability exchange collisions. We discuss in detail the requirements for obtaining good quantum state transfer efficiency and study the possibility to readout the nuclear spin state optically.

Lin Xin, Maryrose Barrios, Julia T. Cohen +1 more

We generate spin squeezed ground states in an atomic spin-1 Bose-Einstein condensate tuned near the quantum-critical point separating the different spin phases of the interacting ensemble using a novel nonadiabatic technique. In contrast to typical nonequilibrium methods for preparing atomic squeezed states by quenching through a quantum phase transition, squeezed ground states are time stationary with a constant quadrature squeezing angle. A squeezed ground state with 6-8 dB of squeezing and a constant squeezing angle is demonstrated. The long-term evolution of the squeezed ground state is measured and shows gradual decrease in the degree of squeezing over 2 s that is well modeled by a slow tuning of the Hamiltonian due to the loss of atomic density. Interestingly, modeling the gradual decrease does not require additional spin decoherence models despite a loss of 75% of the atoms.

Sema Bi̇lge Ocak, T. Altanhan

Feng Peng, Dapeng Ding

Tobias Lühmann, S. Diziain, Jan Meijer +1 more

Among hundreds of optically active solid-state defects, very few of them hold the promise of spin qubits coherently operating at room temperature. Besides the prominent nitrogen-vacancy (NV) center in diamond, the more recently discovered ST1 center possesses advantageous electronic and spin properties such as a spin-free ground state and a large spin readout contrast (>50%) at 300 K. However, because of its unknown nature, the ST1 center was never created on demand or computed theoretically. Here, we show that both oxygen and the lattice vacancy are constituents of the ST1 center. The involvement of oxygen is unambiguously proved from two independent experiments conducted on two different samples. The creation efficiency of ST1 at 1200 °C annealing is about 10 –5 for oxygen implantation of energy 6–50 keV. The addition of vacancies followed by a thermal treatment activate further oxygen into ST1 centers, as it does for native nitrogen into NV centers. Possible ST1 configurations are discussed. The ST1 creation competes with the likely more efficient formation of OV and OVH defects. The controlled fabrication of ST1 and NV centers opens up the way to scalable room-temperature hybrid qubit systems and universal nuclear spin gates.