arXiv subjects

Gabriel E. Patenotte

Publications and source records attributed to Gabriel E. Patenotte.

5 recordsLinked to original sources

arXiv2026

Absence of Far-Detuned Attractive Optical Traps for Alkali Rydberg Atoms

Neutral-atom quantum simulation is susceptible to entanglement between the atom's internal electronic state and its center-of-mass position. In many alkali Rydberg platforms, the 'spin-motion coupling' is exacerbated by the free expansion required to avoid ponderomotive anti-trapping from optical fields. A recent proposal (arXiv:2505.01071) claims sufficiently excited Rydberg states could be trapped in a monochromatic, far-detuned, circularly polarized optical field by harnessing a large vector polarizability. We disprove the proposal through analytic calculation and measurement of the vector polarizability of the $54S$, $54P$, and $53D$ orbitals of Cesium. Regarding the optical angular frequency $ω$, we analytically derive that the scalar, vector, and tensor polarizabilities scale as $ω^{-2}$, $ω^{-3}$, and $ω^{-4}$, as opposed to the proposed scaling of $ω^{-2}$, $ω^{-1}$, and $ω^{-2}$. We refine the sum-over-states expression for vector and tensor polarizability to be numerically stable and predict negligible vector and tensor polarizabilities far detuned from resonances, in agreement with our measurements. However, we find vector polarizability can enhance a recent proposal for near-detuned attractive trapping. Furthermore, we evaluate the breakdown of the electric-dipole approximation and derive no effect stronger than ponderomotive repulsion. We conclude that an attractive, monochromatic, far-detuned optical trap for alkali Rydberg states is not possible, regardless of the beam geometry.

physics.atom-ph↗

arXiv2024

Sub-millisecond Entanglement and iSWAP Gate between Molecular Qubits

Quantum computation (QC) and simulation rely on long-lived qubits with controllable interactions. Early work in quantum computing made use of molecules because of their readily available intramolecular nuclear spin coupling and chemical shifts, along with mature nuclear magnetic resonance techniques. Subsequently, the pursuit of many physical platforms has flourished. Trapped polar molecules have been proposed as a promising quantum computing platform, offering scalability and single-particle addressability while still leveraging inherent complexity and strong couplings of molecules. Recent progress in the single quantum state preparation and coherence of the hyperfine-rotational states of individually trapped molecules allows them to serve as promising qubits, with intermolecular dipolar interactions creating entanglement. However, universal two-qubit gates have not been demonstrated with molecules. Here, we harness intrinsic molecular resources to implement a two-qubit iSWAP gate using individually trapped $X^{1}Σ^{+}$ NaCs molecules. We characterize the innate dipolar interaction between rotational states and control its strength by tuning the polarization of the traps. By allowing the molecules to interact for 664 $μ$s at a distance of 1.9 $μ$m, we create a maximally entangled Bell state with a fidelity of 94(3)\%, following postselection to remove trials with empty traps. Using motion-rotation coupling, we measure residual excitation of the lowest few motional states along the axial trapping direction and find them to be the primary source of decoherence. Finally, we identify two non-interacting hyperfine states within the ground rotational level in which we encode a qubit. The interaction is toggled by transferring between interacting and non-interacting states to realize an iSWAP gate. We verify the gate performance by measuring its logical truth table.

physics.atom-ph↗

arXiv2024

Site-selective preparation and multi-state readout of molecules in optical tweezers

Polar molecules are a quantum resource with rich internal structure that can be coherently controlled. The structure, however, also makes the state preparation and measurement (SPAM) of molecules challenging. We advance the SPAM of individual molecules assembled from constituent atoms trapped in optical tweezer arrays. Sites without NaCs molecules are eliminated using high-fidelity Cs atom detection, increasing the peak molecule filling fraction of the array threefold. We site-selectively initialize the array in a rotational qubit subspace that is insensitive to differential AC Stark shifts from the optical tweezer. Lastly, we detect multiple rotational states per experimental cycle by imaging atoms after sequential state-selective dissociations. These demonstrations extend the SPAM capabilities of molecules for quantum information, simulation, and metrology.

physics.atom-ph↗

arXiv2023

Extended rotational coherence of polar molecules in an elliptically polarized trap

We demonstrate long rotational coherence of individual polar molecules in the motional ground state of an optical trap. In the present, previously unexplored regime, the rotational eigenstates of molecules are dominantly quantized by trapping light rather than static fields, and the main source of decoherence is differential light shift. In an optical tweezer array of NaCs molecules, we achieve a three-orders-of-magnitude reduction in differential light shift by changing the trap's polarization from linear to a specific "magic" ellipticity. With spin-echo pulses, we measure a rotational coherence time of 62(3) ms (one pulse) and 250(40) ms (up to 72 pulses), surpassing the projected duration of resonant dipole-dipole entangling gates by orders of magnitude.

physics.atom-ph↗

arXiv2023

High resolution photoassociation spectroscopy of the excited $c^3Σ_{1}^+$ potential of $^{23}$Na$^{133}$Cs

We report on photoassociation spectroscopy probing the $c^3Σ_{1}^+$ potential of the bi-alkali NaCs molecule, identifying eleven vibrational lines between $v' = 0$ and $v' = 25$ of the excited $c^3Σ_{1}^+$ potential, and resolving their rotational and hyperfine structure. The observed lines are assigned by fitting to an effective Hamiltonian model of the excited state structure with rotational and hyperfine constants as free parameters. We discuss unexpected broadening of select vibrational lines, and its possible link to strong spin-orbit coupling of the $c^3Σ_{1}^+$ potential with the nearby $b^3Π_1$ and $B^1Π_1$ manifolds. Finally we report use of the $v' = 22$ line as an intermediate state for two-photon transfer of weakly bound Feshbach molecules to the rovibrational ground state of the $X^1Σ^+$ manifold.

physics.atom-ph↗