THE EUROPEAN PHYSICAL JOURNAL D Interferometry with entangled atoms

A quantum gravity-gradiometer consists of two spatially separated ensembles of atoms interrogated by pulses of a common laser beam. The laser pulses cause the probability amplitudes of atomic ground-state hyperfine levels to interfere, producing two, motion-sensitive, phase shifts, which allow the measurement of the average acceleration of each ensemble, and, via simple differencing, of the acceleration gradient. Here we propose entangling the quantum states of atoms from the two ensembles prior to the pulse sequence, and show that entanglement encodes their relative acceleration in a single interference phase which can be measured directly, with no need for differencing. PACS. 39.20.+q Atom interferometry techniques – 03.75.Dg Atom and neutron interferometry – 03.67.-a Quantum information – 03.67.Lx Quantum computation