arXiv subjects

S. L. Bromley

Publications and source records attributed to S. L. Bromley.

4 recordsLinked to original sources

arXiv2017

Dynamics of interacting fermions under spin-orbit coupling in an optical lattice clock

Quantum statistics and symmetrization dictate that identical fermions do not interact via s-wave collisions. However, in the presence of spin-orbit coupling (SOC), fermions prepared in identical internal states with distinct momenta become distinguishable. The resulting strongly interacting system can exhibit exotic topological and pairing behaviors, many of which are yet to be observed in condensed matter systems. Ultracold atomic gases offer a promising pathway for simulating these rich phenomena. Two recent experiments reported the observation of single atom SOC in optical lattice clocks (OLCs) based on alkaline-earth atoms. In these works encoding the effective spin degree of freedom in the long-lived electronic clock states significantly reduced the detrimental effects of spontaneous emission and heating that have thus far hindered the study of interacting SOC with alkali atoms. Beyond first studies of interacting SOC with alkali atoms in a bulk gas and with two particles in a lattice, here we enter a new regime of many-body interacting SOC in an OLC. Using clock spectroscopy, we observe the precession of the collective magnetization and the emergence of spin locking effects arising from an interplay between p-wave and SOC-induced exchange interactions. The many-body dynamics are well captured by a collective XXZ spin model, which describes a broad class of condensed matter systems ranging from superconductors to quantum magnets. Furthermore, our work will aid in the design of next-generation OLCs by offering a route for avoiding the observed large density shifts caused by SOC-induced exchange interactions.

physics.atom-ph↗

arXiv2016

Spin-orbit coupled fermions in an optical lattice clock

Engineered spin-orbit coupling (SOC) in cold atom systems can aid in the study of novel synthetic materials and complex condensed matter phenomena. Despite great advances, alkali atom SOC systems are hindered by heating from spontaneous emission, which limits the observation of many-body effects, motivating research into potential alternatives. Here we demonstrate that SOC can be engineered to occur naturally in a one-dimensional fermionic 87Sr optical lattice clock (OLC). In contrast to previous SOC experiments, in this work the SOC is both generated and probed using a direct ultra-narrow optical clock transition between two electronic orbital states. We use clock spectroscopy to prepare lattice band populations, internal electronic states, and quasimomenta, as well as to produce SOC dynamics. The exceptionally long lifetime of the excited clock state (160 s) eliminates decoherence and atom loss from spontaneous emission at all relevant experimental timescales, allowing subsequent momentum- and spin-resolved in situ probing of the SOC band structure and eigenstates. We utilize these capabilities to study Bloch oscillations, spin-momentum locking, and Van Hove singularities in the transition density of states. Our results lay the groundwork for the use of OLCs to probe novel SOC phases of matter.

cond-mat.quant-gas↗

arXiv2014

Spectroscopic observation of SU(N)-symmetric interactions in Sr orbital magnetism

SU(N) symmetry can emerge in a quantum system with N single-particle spin states when spin is decoupled from inter-particle interactions. So far, only indirect evidence for this symmetry exists, and the scattering parameters remain largely unknown. Here we report the first spectroscopic observation of SU(N=10) symmetry in Sr-87 using the state-of-the-art measurement precision offered by an ultra-stable laser. By encoding the electronic orbital degree of freedom in two clock states, while keeping the system open to 10 nuclear spin sublevels, we probe the non-equilibrium two-orbital SU(N) magnetism via Ramsey spectroscopy of atoms confined in an array of two-dimensional optical traps. We study the spin-orbital quantum dynamics and determine all relevant interaction parameters. This work prepares for using alkaline-earth atoms as test-beds for iconic orbital models.

cond-mat.quant-gas↗

arXiv2013

An Optical Lattice Clock with Accuracy and Stability at the $10^{-18}$ Level

The exquisite control exhibited over quantum states of individual particles has revolutionized the field of precision measurement, as exemplified by the most accurate atomic clock realized in single trapped ions. Whereas many-atom lattice clocks have shown advantages in measurement precision over trapped-ion clocks, their accuracy has remained 20 times worse. Here we demonstrate, for the first time, that a many-atom system achieves accuracy (6x10^{-18}) better than a single ion-based clock, with vastly reduced averaging times (3000 s). This is the first time a single clock has achieved the best performance in all three key ingredients necessary for consideration as a primary standard - stability, reproducibility, and accuracy. This work paves the way for future experiments to integrate many-body quantum state engineering into the frontiers of quantum metrology, creating exciting opportunities to advance precision beyond the standard quantum limit. Improved frequency standards will have impact to a wide range of fields from the realization of the SI units, the development of quantum sensors, to precision tests of the fundamental laws of nature.

physics.atom-ph↗