Entanglement in Spatial Adiabatic Processes for Interacting Atoms

Abstract

We study the dynamics of the non-classical correlations for few atom systems in the presence of strong interactions for a number of recently developed adiabatic state preparation protocols. We show that entanglement can be created in a controlled fashion and can be attributed to two distinct sources, the atom-atom interaction and the distribution of atoms among different traps.Keywords Entanglement · Spatial adiabatic passage 1 IntroductionCorrelations between quantum particles are responsible for many properties of advanced solid state systems which cannot be derived from single particle behaviour [1]. Recently these correlations were also recognised as a resource in quantum information and metrology, where they have to be deliberately created and engineered [2]. However, quantum correlations are known to be fragile, and preparing entangled states with high fidelity is often a difficult task [3,4].The Hilbert space of interacting few or many particle systems becomes more complex and crowded, and preparing quantum states in such systems has an additional degree of complexity. However, over the last two decades, systems of ultracold atoms have been developed where control over almost all internal and external degrees of freedom is possible. By today, ground state systems of a handful of particles can be deterministically prepared in laboratories [5], and dynamical control of their center-of-mass degree of freedom is possible using time-dependent electromagnetic fields [6] . The interaction between these ultracold atoms is usually short-range and for many species so-called Feshbach resonances exist, that can be used to adjust the interaction strength [7].One possible strategy for controlling interacting few atom systems is to generalise know single particle protocols. Out of these, one class that allows for high fidelities are adiabatic techniques, where the evolution follows one specific eigenstate at all times. For the control of the centre-of-mass of single particles, these are know as spatial adiabatic passage

Roadmap on STIRAP applications

“…For ultracold atoms one of the main challenges is to identify or design systems where the three tunnel-coupled states are not necessarily the ground states of the potential, in order to create high-fidelity quantum state preparation settings. This is particularly interesting for many-particle systems, where nonclassical correlations and entanglement can be created this way [149]. However, as the densities of typical spectra for many-particle systems quickly become too large for adiabatic processes to be realistic, careful stability analyses and the development of shortcut algorithms becomes important.…”

Spin Entangled State Transfer in Quantum Dot Arrays: Coherent Adiabatic and Speed‐Up Protocols

“…[19,20] Such techniques, known as coherent transfer by adiabatic passage (CTAP), have been extended to more complicated architectures in solid state devices [21][22][23][24] as well as in cold atoms. [25,26] Other proposals consider the level detuning as a control parameter to transfer a qubit state. [27] Recent experiments enable coherent shuttling of electron spin entangled states in QD arrays, [28,29] where one party of an entangled spin pair is adiabatically transferred to a long-distant site by detuning levels.…”

“…A single electron in a TQD can be directly transferred between outer dots by adiabatic passage via a dark state (DS) without ever populating other instantaneous eigenstates of the system [19,20]. Such techniques, known as coherent transfer by adiabatic passage (CTAP), have been extended to more complicated architectures in solid state devices [21][22][23][24] as well as in cold atoms [25,26]. Other proposals consider the level detuning as a control parameter to transfer a qubit state [27].…”