Temperature Sensitivity of N- and N- Ground-State Manifolds.

We measure electron- and nuclear-spin transition frequencies in the ground state of nitrogen-vacancy (N-) centers in diamond for two nitrogen isotopes (N- and N-) over temperatures ranging from 77 to 400 K. Measurements are performed using Ramsey interferometry and direct optical readout of the nuclear and electron spins. We extract coupling parameters (for N-), , , , and , and their temperature dependences for both isotopes.

Dicke State Generation and Extreme Spin Squeezing via Rapid Adiabatic Passage.

Considering the unique energy level structure of the one-axis twisting Hamiltonian in combination with standard rotations, we propose the implementation of a rapid adiabatic passage scheme on the Dicke state basis. The method permits to drive Dicke states of the many-atom system into entangled states with maximum quantum Fisher information. The designed states allow us to overcome the classical limit of phase sensitivity in quantum metrology and sensing.

Two-qubit atomic gates: spatio-temporal control of Rydberg interaction.

By controlling the temporal and spatial features of light, we propose a novel protocol to prepare two-qubit entangling gates on atoms trapped at close distance, which could potentially speed up the operation of the gate from the sub-micro to the nanosecond scale. The protocol is robust to variations in the pulse areas and the position of the atoms, by virtue of the coherent properties of a dark state, which is used to drive the population through Rydberg states. From the time-domain perspective, the protocol generalizes the one proposed by Jaksch and coworkers [Jaksch , , 2000, , 2208], with three pulses that operate symmetrically in time, but with different pulse areas.

Circularly polarized light-induced potentials and the demise of excited states.

In the presence of strong electric fields, the excited states of single-electron molecules and molecules with large transient dipoles become unstable because of anti-alignment, the rotation of the molecular axis perpendicular to the field vector, where bond hardening is not possible. We show how to overcome this problem by using circularly polarized electromagnetic fields. Using a full quantum description of the electronic, vibrational, and rotational degrees of freedom, we characterize the excited electronic state dressed by the field and analyze its dependence on the bond length and angle and the stability of its vibro-rotational eigenstates.

Demonstration of diamond nuclear spin gyroscope.

We demonstrate the operation of a rotation sensor based on the nitrogen-14 (N) nuclear spins intrinsic to nitrogen-vacancy (NV) color centers in diamond. The sensor uses optical polarization and readout of the nuclei and a radio-frequency double-quantum pulse protocol that monitors N nuclear spin precession. This measurement protocol suppresses the sensitivity to temperature variations in the N quadrupole splitting, and it does not require microwave pulses resonant with the NV electron spin transitions.