Abstract
We propose a novel and robust technique to realize a beam splitter for trapped Bose–Einstein condensates (BECs). The scheme relies on the possibility of producing different potentials simultaneously for two internal atomic states. The atoms are coherently transferred, via a Rabi coupling between the two long-lived internal states, from a single well potential to a double-well. We present numerical simulations supporting our proposal and confirming excellent efficiency and fidelity of the transfer process with realistic numbers for a BEC of 87Rb. We discuss the experimental implementation by suggesting state-selective microwave (MW) potentials as an ideal tool to be exploited for magnetically trapped atoms. The working principles of this technique are tested on our atom chip device which features an integrated coplanar MW guide. In particular, the first realization of a double-well potential by using a MW dressing field is reported. Experimental results are presented together with numerical simulations, showing good agreement. Simultaneous and independent control on the external potentials is also demonstrated in the two Rubidium clock states. The transfer between the two states, featuring respectively a single and a double-well, is characterized and it is used to measure the energy spectrum of the atoms in the double-well. Our results show that the spatial overlap between the two states is crucial to ensure the functioning of the beamsplitter. Even though this condition could not be achieved in our current setup, the proposed technique can be realized with current state-of-the-art devices being particularly well suited for atom chip experiments. We anticipate applications in quantum enhanced interferometry.
Highlights
In recent years, Bose–Einstein condensates (BECs) have proven to be appealing systems for the realization of atom interferometers, owing to their properties of macroscopic phase coherence [1]
Even though they are not yet better performing than the best state-of-the-art atom interferometers, which are mainly limited by shot-noise, BEC based in-trap interferometers will be crucial for local probing on the scale of few microns, due to their small size, and for application requiring a relatively low atom number
State-of-the-art BECs interferometers suffer from technical noise as finite temperature effects, excitations, detection noise as well as phase diffusion in configurations working with trapped atomic ensembles [5] which limit the phase sensitivity above the standard quantum limit
Summary
Bose–Einstein condensates (BECs) have proven to be appealing systems for the realization of atom interferometers, owing to their properties of macroscopic phase coherence [1]. Much effort has been dedicated through the years to optimize these same techniques while novel ones, capable of definitely solving these problems, have not been found yet To accomplish this task, we propose here a novel scheme for a robust and fast beam splitter with trapped BECs which does not require a dynamical variation of the trapping potential, neither a momentum transfer to the atoms. We perform numerical simulations of this scheme, demonstrating nearly unitary efficiency in the transfer to the ground state of the double-well potential. As it concerns the experimental implementation, this requires the realization of external potentials which are different for the two internal states, ∣1〉 and ∣2〉, and to create a double-well for the state ∣2〉. We discuss further experimental developments by means of state-of-the-art devices and possible applications of the presented technique
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