Abstract Optical tweezers are used to facilitate cold collisions between two Rydberg rubidium atoms (87Rb) by controlling the impact parameter and collision energy. One atom is held stationary while the other is propelled to a constant velocity. After the tweezers are deactivated, both atoms are excited to a Rydberg state using a π-pulse. Following the collision, a second π-pulse is applied. If the stationary atom undergoes minimal momentum transfer and returns to its ground state, it can be recaptured when the tweezer is reactivated. The collision probability as a function of the impact parameter is extracted from the atom loss in the tweezer and used to determine the collisional cross section between Rydberg atoms. Numerical simulations of elastic two-body collisions agree well with the experimental data, providing valuable insights into the parameter regime where quantum effects will become important.
Abstract Optical tweezers are used to facilitate cold collisions between two Rydberg rubidium atoms (87Rb) by controlling the impact parameter and collision energy. One atom is held stationary while the other is propelled to a constant velocity. After the tweezers are deactivated, both atoms are excited to a Rydberg state using a π-pulse. Following the collision, a second π-pulse is applied. If the stationary atom undergoes minimal momentum transfer and returns to its ground state, it can be recaptured when the tweezer is reactivated. The collision probability as a function of the impact parameter is extracted from the atom loss in the tweezer and used to determine the collisional cross section between Rydberg atoms. Numerical simulations of elastic two-body collisions agree well with the experimental data, providing valuable insights into the parameter regime where quantum effects will become important.
The inherent polarization gradients in tight optical tweezers can be used to couple the atomic spins to the two-body motion under the action of a microwave spin-flip transition, so that such a spin-motion coupling offers an important control knob on the motional states of optically trapped two colliding atoms. Here, after preparing two elastically scattering 85Rb atoms in the three-dimensional ground-state in the optical tweezer, we employed this control in order to probe the colliding energies of elastic and inelastic channels. The combination of microwave spectra and corresponding s-wave pseudopotential model allows us to infer the effect of the state-dependent trapping potentials on the elastic colliding energies, as well as to reveal how the presence of inelastic interactions affects elastic part of the relative potential. Our work shows that the spin-motion coupling in a tight optical tweezer expand the experimental toolbox for fundamental studies of ultracold collisions in the two body systems with reactive collisions, and potentially for that of more complex interactions, such as optically trapped atom-molecule and molecule-molecule interactions.
Continuously replenished optical tweezer arrays will unlock unlimited-depth quantum circuits with neutral atom qubits. A key bottleneck limiting the cycle time of these systems is removing atoms from tweezers initially loaded with more than one atom. In the conventional technique of light-assisted collisions, slow collisional dynamics limit the timescale for removing excess atoms to several milliseconds. Here, we propose and demonstrate a scheme for selectively removing one atom at a time from multiply occupied tweezers on a microsecond timescale, using intra-tweezer Rydberg blockade and autoionization. We demonstrate the protocol in Yb 171 in two complementary regimes. With two-photon Rydberg excitation from the ground state, we reduce the multi-atom probability to 1% in 64.8 μ s , while retaining single atoms in 58.2 ( 2 ) % of the tweezers, which is comparable to the filling fraction achieved with light-assisted collisions under the same experimental conditions, but over two orders of magnitude faster. With single-photon excitation from the metastable state P 0 3 , reduced single-atom loss enables a higher filling fraction of 74.8 ( 3 ) % , at the cost of additional temporal overhead to prepare the atoms in P 0 3 . The final filling fraction is limited by an unexplained two-body loss mechanism, which, if solved, could enable fast, quasi-deterministic loading.
Continuously replenished optical tweezer arrays will unlock unlimited-depth quantum circuits with neutral atom qubits. A key bottleneck limiting the cycle time of these systems is removing atoms from tweezers initially loaded with more than one atom. In the conventional technique of light-assisted collisions, slow collisional dynamics limit the timescale for removing excess atoms to several milliseconds. Here, we propose and demonstrate a scheme for selectively removing one atom at a time from multiply occupied tweezers on a microsecond timescale, using intra-tweezer Rydberg blockade and autoionization. We demonstrate the protocol in 171Yb in two complementary regimes. With two-photon Rydberg excitation from the ground state, we reduce multi-atom probability to 1% in 64.8 μs, while retaining single atoms in 58.2(2)% of the tweezers, which is comparable to the filling fraction achieved with light-assisted collisions under the same experimental conditions, but over two orders of magnitude faster. With single-photon excitation from the metastable state 3P0, reduced single-atom loss enables a higher filling fraction of 74.8(3)%, at the cost of additional temporal overhead to prepare the atoms in 3P0. The final filling fraction is limited by an unexplained two-body loss mechanism, which, if solved, could enable fast, quasi-deterministic loading.
Rydberg atoms feature extremely strong interactions, in particular between states of opposite electronic parity. In a room temperature environment, these states are inevitably populated due to black-body radiation, leading to many-body dephasing. Here we report on a controlled microscopic study of the resulting interactions, which we probe single atom resolved by facilitated excitation in an optical tweezer array. We identify motion of the excited atoms to be of prime importance for the process, which can be used to mitigate the impact of the state contamination on 2D quantum simulators.
Abstract The advent of single-atom trapping in optical tweezers and experimental evolution in control, isolation, and manipulation of cold atoms allows us to manifest the few-body physics and its connection with the many-body systems. In cold atom experiments, the universality of few-body physics is majorly governed by the scattering length which makes it an important parameter in determining theoretically calculated loss rates. Here, we numerically study the 3-body collisional dynamics for Cesium atoms using the atom loss model described by Born-Markov approximation. Using the Cs atoms provides us the freedom to vary the scattering length, a , as a function of the magnetic field through Feshbach resonances. We investigate the three-, two-, and one-particle processes in the repulsive interactions regime at different values for a . We find that the probability of one atom remaining in the trap is maximum at B = 26 G corresponding to a = 402.382 a 0 and has the highest value amongst the probability of zero-, two-, and three-particle remaining in the trap at same magnetic field after the collision. Our findings leads to high fidelity single atom tweezers which have direct application in creating defect free arrays for quantum information processing purposes.
Coupling electronic and vibrational degrees of freedom of Rydberg atoms held in optical tweezer arrays offers a flexible mechanism for creating and controlling atom-atom interactions. We find that the state-dependent coupling between Rydberg atoms and local oscillator modes gives rise to two- and three-body interactions which are controllable through the strength of the local confinement. This approach even permits the cancellation of two-body terms such that three-body interactions become dominant. We analyze the structure of these interactions on two-dimensional bipartite lattice geometries and explore the impact of three-body interactions on system ground state on a square lattice. Focusing specifically on a system of ^{87}Rb atoms, we show that the effects of the multibody interactions can be maximized via a tailored dressed potential within a trapping frequency range of the order of a few hundred kilohertz and for temperatures corresponding to a >90% occupation of the atomic vibrational ground state. These parameters, as well as the multibody induced timescales, are compatible with state-of-the-art arrays of optical tweezers. Our work shows a highly versatile handle for engineering multibody interactions of quantum many-body systems in most recent manifestations on Rydberg lattice quantum simulators.