arXiv subjects

Matthew A. Norcia

Publications and source records attributed to Matthew A. Norcia.

At least 19 recordsLinked to original sources

arXiv2025

Fault-tolerant quantum computation with a neutral atom processor

Quantum computing experiments are transitioning from running on physical qubits to using encoded, logical qubits. Fault-tolerant computation can identify and correct errors, and has the potential to enable the dramatically reduced logical error rates required for valuable algorithms. However, it requires flexible control of high-fidelity operations performed on large numbers of qubits. We demonstrate fault-tolerant quantum computation on a quantum processor with 256 qubits, each an individual neutral Ytterbium atom. The operations are designed so that key error sources convert to atom loss, which can be detected by imaging. Full connectivity is enabled by atom movement. We demonstrate the entanglement of 24 logical qubits encoded into 48 atoms, at once catching errors and correcting for, on average 1.8, lost atoms. We also implement the Bernstein-Vazirani algorithm with up to 28 logical qubits encoded into 112 atoms, showing better-than-physical error rates. In both cases, "erasure conversion," changing errors into a form that can be detected independently from qubit state, improves circuit performance. These results begin to clear a path for achieving scientific quantum advantage with a programmable neutral atom quantum processor.

quant-ph↗

arXiv2022

Two-Dimensional Supersolid Formation in Dipolar Condensates

Dipolar condensates have recently been coaxed to form the long-sought supersolid phase. While one-dimensional supersolids may be prepared by triggering a roton instability, we find that such a procedure in two dimensions (2D) leads to a loss of both global phase coherence and crystalline order. Unlike in 1D, the 2D roton modes have little in common with the supersolid configuration. We develop a finite-temperature stochastic Gross-Pitaevskii theory that includes beyond-mean-field effects to explore the formation process in 2D and find that evaporative cooling directly into the supersolid phase--hence bypassing the first-order roton instability--can produce a robust supersolid in a circular trap. Importantly, the resulting supersolid is stable at the final nonzero temperature. We then experimentally produce a 2D supersolid in a near-circular trap through such an evaporative procedure. Our work provides insight into the process of supersolid formation in 2D and defines a realistic path to the formation of large two-dimensional supersolid arrays.

cond-mat.quant-gas↗

arXiv2021

Maintaining supersolidity in one and two dimensions

We theoretically investigate supersolidity in three-dimensional dipolar Bose-Einstein condensates. We focus on the role of trap geometry in determining the dimensionality of the resulting droplet arrays, which range from one-dimensional to zigzag, through to two-dimensional supersolids in circular traps. Supersolidity is well established in one-dimensional arrays, and may be just as favorable in two-dimensional arrays provided that one appropriately scales the atom number to the trap volume. We develop a tractable variational model--which we benchmark against full numerical simulations--and use it to study droplet crystals and their excitations. We also outline how exotic ring and stripe states may be created with experimentally-feasible parameters. Our work paves the way for future studies of two-dimensional dipolar supersolids in realistic settings.

cond-mat.quant-gas↗

arXiv2021

Can angular oscillations probe superfluidity in dipolar supersolids?

Angular oscillations can provide a useful probe of the superfluid properties of a system. Such measurements have recently been applied to dipolar supersolids, which exhibit both density modulation and phase coherence, and for which robust probes of superfluidity are particularly interesting. So far, these investigations have been confined to linear droplet arrays. Here, we explore angular oscillations in systems with 2D structure, which in principle have greater sensitivity to superfluidity. Surprisingly, in both experiment and simulation, we find that the frequency of angular oscillations remains nearly unchanged even when the superfluidity of the system is altered dramatically. This indicates that angular oscillation measurements do not always provide a robust experimental probe of superfluidity with typical experimental protocols.

cond-mat.quant-gas↗

arXiv2021

New opportunites for interactions and control with ultracold lanthanides

Lanthanide atoms have an unusual electron configuration, with a partially filled shell of $f$ orbitals. This leads to a set of characteristic properties that enable enhanced control over ultracold atoms and their interactions: large numbers of optical transitions with widely varying wavelengths and transition strengths, anisotropic interaction properties between atoms and with light, and a large magnetic moment and spin space present in the ground state. These features in turn enable applications ranging from narrow-line laser cooling and spin manipulation to evaporative cooling through universal dipolar scattering, to the observation of a rotonic dispersion relation, self-bound liquid-like droplets stabilized by quantum fluctuations, and supersolid states. In this short review, we describe how the unusual level structure of lanthanide atoms leads to these key features, and provide a brief and necessarily partial overview of experimental progress in this rapidly developing field.

cond-mat.quant-gas↗

arXiv2021

Entropy transfer from a quantum particle to a classical coherent light field

In the field of light-matter interactions, it is often assumed that a classical light field that interacts with a quantum particle remains almost unchanged and thus contains nearly no information about the manipulated particles. To investigate the validity of this assumption, we develop and theoretically analyze a simple Gedankenexperiment which involves the interaction of a coherent state with a quantum particle in an optical cavity. We quantify the resulting alteration of the light field by measuring the fidelity of its initial and equilibrium states. Using Bayesian inference, we demonstrate the information transfer through photon measurements. In addition, we employ the concepts of quantum entropy and mutual information to quantify the entropy transfer from the particle to the light field. In the weak coupling limit, we validate the usually assumed negligible alteration of the light field and entropy transfer. In the strong coupling limit, however, we observe that the information of the initial particle state can be fully encoded in the light field, even for large photon numbers. Nevertheless, we show that spontaneous emission is a sufficient mechanism for removing the entropy initially stored in the particle. Our analysis provides a deeper understanding of the entropy exchange between quantum matter and classical light.

quant-ph↗

arXiv2021

Birth, life, and death of a dipolar supersolid

In the short time since the first observation of supersolid states of ultracold dipolar atoms, substantial progress has been made in understanding the zero-temperature phase diagram and low-energy excitations of these systems. Less is known, however, about their finite-temperature properties, particularly relevant for supersolids formed by cooling through direct evaporation. Here, we explore this realm by characterizing the evaporative formation and subsequent decay of a dipolar supersolid by combining high-resolution in-trap imaging with time-of-flight observables. As our atomic system cools towards quantum degeneracy, it first undergoes a transition from thermal gas to a crystalline state with the appearance of periodic density modulation. This is followed by a transition to a supersolid state with the emergence of long-range phase coherence. Further, we explore the role of temperature in the development of the modulated state.

cond-mat.quant-gas↗

arXiv2021

Two-dimensional supersolidity in a dipolar quantum gas

Supersolidity -- a quantum-mechanical phenomenon characterized by the presence of both superfluidity and crystalline order -- was initially envisioned in the context of bulk solid helium, as a possible answer to the question of whether a solid could have superfluid properties. While supersolidity has not been observed in solid helium (despite much effort), ultracold atomic gases have provided a fundamentally new approach, recently enabling the observation and study of supersolids with dipolar atoms. However, unlike the proposed phenomena in helium, these gaseous systems have so far only shown supersolidity along a single direction. By crossing a structural phase transition similar to those occurring in ionic chains, quantum wires, and theoretically in chains of individual dipolar particles, we demonstrate the extension of supersolid properties into two dimensions, providing an important step closer to the bulk situation envisioned in helium. This opens the possibility of studying rich excitation properties, including vortex formation, as well as ground-state phases with varied geometrical structure in a highly flexible and controllable system.

cond-mat.quant-gas↗

arXiv2020

A tweezer clock with half-minute atomic coherence at optical frequencies and high relative stability

The preparation of large, low-entropy, highly coherent ensembles of identical quantum systems is foundational for many studies in quantum metrology, simulation, and information. Here, we realize these features by leveraging the favorable properties of tweezer-trapped alkaline-earth atoms while introducing a new, hybrid approach to tailoring optical potentials that balances scalability, high-fidelity state preparation, site-resolved readout, and preservation of atomic coherence. With this approach, we achieve trapping and optical clock excited-state lifetimes exceeding $ 40 $ seconds in ensembles of approximately $ 150 $ atoms. This leads to half-minute-scale atomic coherence on an optical clock transition, corresponding to quality factors well in excess of $10^{16}$. These coherence times and atom numbers reduce the effect of quantum projection noise to a level that is on par with leading atomic systems, yielding a relative fractional frequency stability of $5.2(3)\times10^{-17}~(τ/s)^{-1/2}$ for synchronous clock comparisons between sub-ensembles within the tweezer array. When further combined with the microscopic control and readout available in this system, these results pave the way towards long-lived engineered entanglement on an optical clock transition in tailored atom arrays.

physics.atom-ph↗

arXiv2020

Feshbach Resonances in an Erbium-Dysprosium Dipolar Mixture

We report on the observation of heteronuclear magnetic Feshbach resonances in several isotope mixtures of the highly magnetic elements erbium and dysprosium. Among many narrow features, we identify two resonances with a width greater than one Gauss. We characterize one of these resonances, in a mixture of $^{168}$Er and $^{164}$Dy, in terms of loss rates and elastic cross section, and observe a temperature dependence of the on-resonance loss rate suggestive of a universal scaling associated with broad resonances. Our observations hold promise for the use of such a resonance for tuning the interspecies scattering properties in a dipolar mixture. We further compare the prevalence of narrow resonances in an $^{168}$Er-$^{164}$Dy mixture to the single-species case, and observe an increased density of resonances in the mixture.

cond-mat.quant-gas↗

arXiv2019

Coupling atoms to cavities with narrow linewidth optical transitions: Applications to frequency metrology

Narrow linewidth optical atomic transitions provide a valuable resource for frequency metrology, and form the basis of today's most precise and accurate clocks. Recent experiments have demonstrated that ensembles of atoms can be interfaced with the mode of an optical cavity using such transitions, and that atom-cavity interactions can dominate over decoherence processes even when the atomic transition that mediates the interactions is very weak. This scenario enables new opportunities for optical frequency metrology, including techniques for nondestructive readout and entanglement enhancement for optical lattice clocks, methods for cavity-enhanced laser frequency stabilization, and high-precision active optical frequency references based on superradiant emission. This tutorial provides a pedagogical description of the physics governing atom-cavity coupling with narrow linewidth optical transitions, and describes several examples of applications to optical frequency metrology.

physics.atom-ph↗

arXiv2019

Seconds-scale coherence in a tweezer-array optical clock

Optical clocks based on atoms and ions achieve exceptional precision and accuracy, with applications to relativistic geodesy, tests of relativity, and searches for dark matter. Achieving such performance requires balancing competing desirable features, including a high particle number, isolation of atoms from collisions, insensitivity to motional effects, and high duty-cycle operation. Here we demonstrate a new platform based on arrays of ultracold strontium atoms confined within optical tweezers that realizes a novel combination of these features by providing a scalable platform for isolated atoms that can be interrogated multiple times. With this tweezer-array clock, we achieve greater than 3 second coherence times and record duty cycles up to 96%, as well as stability commensurate with leading platforms. By using optical tweezer arrays --- a proven platform for the controlled creation of entanglement through microscopic control --- this work further promises a new path toward combining entanglement enhanced sensitivities with the most precise optical clock transitions.

physics.atom-ph↗

arXiv2018

Laser Cooling by Sawtooth Wave Adiabatic Passage

We provide a theoretical analysis for a recently demonstrated cooling method. Two-level particles undergo successive adiabatic transfers upon interaction with counter-propagating laser beams that are repeatedly swept over the transition frequency. We show that particles with narrow linewidth transitions can be cooled to near the recoil limit. This cooling mechanism has a reduced reliance on spontaneous emission compared to Doppler cooling, and hence shows promise for application to systems lacking closed cycling transitions, such as molecules.

quant-ph↗

arXiv2018

A Robust Narrow-Line Magneto-Optical Trap using Adiabatic Transfer

We characterize the properties of a new form of magneto-optical trap (MOT) that relies on non-equilibrium population dynamics associated with narrow-linewidth optical transitions. We demonstrate this mechanism using the 7.5 kHz linewidth transition in both bosonic and fermionic strontium isotopes. In contrast to standard narrow-line MOTs based on imbalances in equilibrium scattering rates, our system benefits from a less complex laser system, a larger capture fraction from higher temperature samples, robustness against experimental perturbations and the ability to operate in the presence of large inhomogeneous broadening of the atomic transition frequency.

physics.atom-ph↗

arXiv2017

Frequency measurements of superradiance from the strontium clock transition

We present the first characterization of the spectral properties of superradiant light emitted from the ultra-narrow, 1 mHz linewidth optical clock transition in an ensemble of cold $^{87}$Sr atoms. Such a light source has been proposed as a next-generation active atomic frequency reference, with the potential to enable high-precision optical frequency references to be used outside laboratory environments. By comparing the frequency of our superradiant source to that of a state-of-the-art cavity-stabilized laser and optical lattice clock, we observe a fractional Allan deviation of $6.7(1)\times 10^{-16}$ at 1 second of averaging, establish absolute accuracy at the 2 Hz ($4\times 10^{-15}$ fractional frequency) level, and demonstrate insensitivity to key environmental perturbations.

physics.atom-ph↗

arXiv2017

Role of atoms in atomic gravitational-wave detectors

Recently, it has been proposed that space-based atomic sensors may be used to detect gravitational waves. These proposals describe the sensors either as clocks or as atom interferometers. Here, we seek to explore the fundamental similarities and differences between the two types of proposals. We present a framework in which the fundamental mechanism for sensitivity is identical for clock and atom interferometer proposals, with the key difference being whether or not the atoms are tightly confined by an external potential. With this interpretation in mind, we propose two major enhancements to detectors using confined atoms, which allow for an enhanced sensitivity analogous to large-momentum-transfer (LMT) used in atom interferometry (though with no transfer of momentum to the atoms), and a way to extend the useful coherence time of the sensor beyond the atom's excited state lifetime.

physics.atom-ph↗

arXiv2017

Cavity Mediated Collective Spin Exchange Interactions in a Strontium Superradiant Laser

Laser cooled and quantum degenerate atoms are widely being pursued as quantum simulators that may explain the behavior of strongly correlated material systems, and as the basis of today's most precise sensors. A key challenge towards these goals is to understand and control coherent interactions between the atoms. Here, we observe long-range exchange interactions mediated by an optical cavity, which manifest as tunable spin-spin interactions on the pseudo spin-1/2 system composed of the millihertz linewidth clock transition in strontium. We observe the so-called one axis twisting dynamics, the emergence of a many-body energy gap, and signatures of gap protection of the optical coherence against certain sources of decoherence. These effects manifest in the output of a pulsed, superradiant laser operating on the millihertz linewidth transition. Our observations will aid in the future design of versatile quantum simulators that take advantage of the unique control and probing capabilities of cavity QED and the rich internal structure of long-lived Sr atoms. They also open a route for the next generation of atomic clocks that utilize quantum correlations for enhanced metrology.

physics.atom-ph↗

arXiv2017

Narrow-line Laser Cooling by Adiabatic Transfer

We propose and demonstrate a novel laser cooling mechanism applicable to particles with narrow-linewidth optical transitions. By sweeping the frequency of counter-propagating laser beams in a sawtooth manner, we cause adiabatic transfer back and forth between the ground state and a long-lived optically excited state. The time-ordering of these adiabatic transfers is determined by Doppler shifts, which ensures that the associated photon recoils are in the opposite direction to the particle's motion. This ultimately leads to a robust cooling mechanism capable of exerting large forces via a weak transition and with reduced reliance on spontaneous emission. We present a simple intuitive model for the resulting frictional force, and directly demonstrate its efficacy for increasing the total phase-space density of an atomic ensemble. We rely on both simulation and experimental studies using the 7.5~kHz linewidth $^1$S$_0$ to $^3$P$_1$ transition in $^{88}$Sr. The reduced reliance on spontaneous emission may allow this adiabatic sweep method to be a useful tool for cooling particles that lack closed cycling transitions, such as molecules.

physics.atom-ph↗