The Science

Quantum superposition lies at the heart of quantum theory, allowing two classically distinct and exclusive alternatives to coexist. This well tested cornerstone of quantum mechanics will be exploited to produce quantum sensors based on laser cooling and trapping methods. These methods, for which the Nobel Prize was awarded in 1997, are used to prepare atoms and ions in a well-controlled motional state.

Tailored laser or microwave pulses are then used to create superposition states and recombine them after some measurement time, leading to interference in final state populations. The form of the pulses, laser geometry, and traps determines the measurement type. Separating the paths vertically, or so that they enclose an area, enables the measurement of gravity and rotation respectively.

Superposing different spin, or energy, states allows magnetic fields or time to be determined. In each case, the result is read out by state-selective detection of the relative population of the final states.