Exploiting Nonclassical Motion of a Trapped Ion Crystal for Quantum-Enhanced Metrology of Global and Differential Spin Rotations.

We theoretically investigate prospects for the creation of nonclassical spin states in trapped ion arrays by coupling to a squeezed state of the collective motion of the ions. The correlations of the generated spin states can be tailored for quantum-enhanced sensing of global or differential rotations of subensembles of the spins by working with specific vibrational modes of the ion array. We propose a pair of protocols to utilize the generated states and demonstrate their viability even for small systems, while assessing limitations imposed by spin-motion entanglement and technical noise. Our work suggests new opportunities for the preparation of many-body states with tailored correlations for quantum-enhanced metrology in spin-boson systems.

Protected State Transfer via an Approximate Quantum Adder.

We propose a decoherence protected protocol for sending single photon quantum states through depolarizing channels. This protocol is implemented via an approximate quantum adder engineered through spontaneous parametric down converters, and shows higher success probability than distilled quantum teleportation protocols for distances below a threshold depending on the properties of the channel.

Experimental demonstration of a secondary source of partially polarized states.

We present a simple device that works as a secondary source of light with prescribed polarization properties. The device has great versatility, allowing complete control over both the degree of polarization and the Stokes vector that belongs to the fully polarized component of partially polarized light beams. We report experimental results that illustrate the device's versatility, by showing how polarized states can be moved within the Poincaré ball along spiraling paths.