Atom-Light Hybrid Interferometer

Abstract

A new type of hybrid atom-light interferometer is demonstrated with atomic Raman amplification processes replacing the beam splitting elements in a traditional interferometer. This nonconventional interferometer involves correlated optical and atomic waves in the two arms. The correlation between atoms and light developed with the Raman process makes this interferometer different from conventional interferometers with linear beam splitters. It is observed that the high-contrast interference fringes are sensitive to the optical phase via a path change as well as the atomic phase via a magnetic field change. This new atom-light correlated hybrid interferometer is a sensitive probe of the atomic internal state and should find wide applications in precision measurement and quantum control with atoms and photons. [4]. They are widely used in precision measurement of a variety of physical quantities. Building on this foundation, nonconventional interferometers can be constructed with nonlinear processes such as wave splitting and recombination elements [5][6][7][8][9][10], as shown in the inset of Fig. 1.Different from the conventional interferometers with beam splitters, the involvement of nonlinear processes in the nonconventional interferometers allows the coupling between two waves of different types, and it can lead to interference fringes that are sensitive to different types of phase shifts. We thus use the word "hybrid" to label these interferometers involving different types of waves. In fact, hybrid interference also occurs via coherent interactions between atoms and light in phenomena such as quantum storage in electromagnetically induced transparency [11][12][13], gradient echo memory [14,15], and slow light [16][17][18][19][20]. However, the hybrid interference effects in these phenomena are in essence still of the same type as the conventional interference effect where the input wave is linearly split into a linear superposition of atom and light fields in the form of a polariton state [11,15]. On the other hand, a nonconventional SU(1,1) interferometer [5,9,10,21] utilizes parametric amplifiers as wave splitting and recombination elements and performs quite differently from the conventional linear interferometers. The name SU(1,1) comes from the nonlinear interaction Hamiltonian for the parametric process [5]:which amplifies an input signal field (â s ) and produces a correlated idler field (â i ) simultaneously. The idler field is coherent with the input field, thus realizing coherent wave splitting.One of the nonlinear processes described by Eq. (1) is the collective atomic Raman amplification process, which FIG. 1 (color online). Experimental sketch for the hybrid atomlight interferometer. A strong Raman write beam (W 1 , red) and a Stokes input field (S 0 , blue) in orthogonal polarization interact with a Λ-shaped atomic system to generate an amplified Stokes field (S 1 ) and a correlated atomic spin wave S a that stays in the atomic system. The amplified Stokes beam (S 1 ), after reflection (S 0 1...

Optimal phase measurements with bright- and vacuum-seeded SU(1,1) interferometers

“…of a substantial improvement over the SQL. The SU(1,1) interferometer was originally conceived by Yurke et al in 1986 [4], but only recently has there been progress towards constructing an interferometer with various platforms, such as light [5][6][7], atoms [8] and light-atom hybrids [9]. This has raised interest in understanding its operation and phase-sensing ability in more detail.…”

The phase sensitivity of a fully quantum three-mode nonlinear interferometer

“…In section 3, we pointed out that the phase can be obtained from the mean number N out of signal (or idler) photons at the output of the NLI. Thus, we estimated the phase uncertainty from error propagation of N out , equation (9). However, we may use any other estimator formula for the phase based on the output signal (or idler, or pump) statistics, like the root mean squared of signal photons, just to mention one example.…”

“…According to the Cramér-Rao bound, the phase uncertainty Δf FI limits the phase uncertainty from below, i.e. Δf FI Δf, with Δf given by equation (9). We emphasize that, even though we know that the phase uncertainty is bounded by the Fisher information, the estimator itself is not specified.…”

“…NLIs also serve to shape and generate bright radiation with quantum properties [7]. The concept can be applied to hybrid atom-light systems to study nonlinear dynamics in entangled systems [8] or perform magnetometry beyond the shot-noise level [9].…”

Optimum quantum resource distribution for phase measurement and quantum information tapping in a dual-beam SU(1,1) interferometer

“…The loss tolerance property shows that dual-beam sensing SUI has great potentials in those situations when quantum efficiency of detection system limits the implementation of quantum enhanced measurement, such as those working at wavelength that lacks efficient photo-detectors (for example, wavelength longer than 2 µm or ultra violet region).Although the dual-beam sensing scheme has twice the SNR as the single-beam sensing scheme, its implementation requires the two correlated beams to be nearly the same so as to probe the same phase change. Very often SUI is realized with different types of waves as in the atom-light hybrid interferometer [25] where the phases involved belong to light and atom separately. In this case the dual beam scheme wouldn't work.…”