Pumped-Up SU(1,1) Interferometry

Abstract

Although SU(1,1) interferometry achieves Heisenberg-limited sensitivities, it suffers from one major drawback: Only those particles outcoupled from the pump mode contribute to the phase measurement. Since the number of particles outcoupled to these "side modes" is typically small, this limits the interferometer's absolute sensitivity. We propose an alternative "pumped-up" approach where all the input particles participate in the phase measurement and show how this can be implemented in spinor BoseEinstein condensates and hybrid atom-light systems-both of which have experimentally realized SU(1,1) interferometry. We demonstrate that pumped-up schemes are capable of surpassing the shot-noise limit with respect to the total number of input particles and are never worse than conventional SU (1,1) interferometry. Finally, we show that pumped-up schemes continue to excel-both absolutely and in comparison to conventional SU(1,1) interferometry-in the presence of particle losses, poor particleresolution detection, and noise on the relative phase difference between the two side modes. Pumped-up SU(1,1) interferometry therefore pushes the advantages of conventional SU(1,1) interferometry into the regime of high absolute sensitivity, which is a necessary condition for useful quantum-enhanced devices.

Machine-Designed Sensor to Make Optimal Use of Entanglement-Generating Dynamics for Quantum Sensing

“…seperate statepreparation and interrogation stages), we simply optimised the controllable parameters of the system using the final sensitivity as the appropriate metric. The significant increase in performance that this approach pro-vides indicates the power of this technique, and could be used in other quantum-enhanced sensing protocols that involve the use of a controllable dynamic parameter, such as when coherent coupling pulses are used to increase the entangled population spontaneously generated from spinchanging collisions [41,47,48], four-wave mixing [49], or Raman superradiance [50,51]. Finally, we note that while this scheme is capable of enhancing the sensitivity of atomic clocks and magnetometers, the continuous use of coupling pulses is incompatible with atomic gravimeters and accelerometers due the the requirement of spacetime separated modes [1,52].…”

“…It was found in previous work that robustness to detection noise could be drastically improved by adding an interaction-based readout (IBR), which is a period of evolution after the interrogation time, to convert the final probability distribution into one that is more robust to detection noise [24,27,35,36]. This often involves reversal of the initial state preparation dynamics (commonly referred to as an 'echo') to restore the initial coherent spin-state [37][38][39][40][41][42][43][44][45]. However, it was shown in [46] that there are schemes that perform significantly better than this.…”

Quantum noise in bright soliton matterwave interferometry

“…We simulate the dynamics of the system by using a stochastic phase space technique known as the truncated Wigner (TW) method, which has previously been used to model the dynamics of quantum gases [40][41][42][43], and unlike the GPE, can be used to model non-classical particle correlations [44][45][46]. The derivation of the TW method has been described in detail elsewhere [40,47,48].…”

Optimal quantum interferometry robust to detection noise using spin-1 atomic condensates

“…The interaction-based readout, very nicely introduced and explained e.g. in [21][22][23][24], helps to avoid direct detection of entangled states, and therefore, protects against the noise effect. Typically, it is done by the timereversed evolution and we will start our analysis with this protocol.…”

“…Utility of the non-classical states in quantum interferometry typically requires detection of particles with very low noise [20], which is hardly achievable with atomic-based technology. Recently, the concept of interaction-based readout [21][22][23][24][25] were proposed, and verified experimentally [7] for some special case, in order to overcome the detection noise problem. The interaction-based readout is nothing else but a unitary evolution applied to the quantum interferometer after the phase encoding step, but before the measurement takes place.…”