Publications Thomas BLAND

2022

Articles

Lauritz Klaus, Thomas Bland, Elena Poli, Claudia Politi, Giacomo Lamporesi, Eva Casotti, R. N. Bisset, Manfred J. Mark, Francesca Ferlaino Observation of vortices and vortex stripes in a dipolar condensate, Nature Phys. (2022-10-31), http://dx.doi.org/10.1038/s41567-022-01793-8 doi:10.1038/s41567-022-01793-8 (ID: 720846)
G. Natale, T. Bland, Simon Gschwendtner, Louis Lafforgue, Daniel S. Grün, A. Patscheider, Manfred J. Mark, F. Ferlaino Bloch oscillations and matter-wave localization of a dipolar quantum gas in a one-dimensional lattice, Communications Physics 5 227 (2022-09-15), http://dx.doi.org/10.1038/s42005-022-01009-8 doi:10.1038/s42005-022-01009-8 (ID: 720840) Toggle Abstract
Three-dimensional quantum gases of strongly dipolar atoms can undergo a crossover from a dilute gas to a dense macrodroplet, stabilized by quantum fluctuations. Adding a one-dimensional optical lattice creates a platform where quantum fluctuations are still unexplored, and a rich variety of new phases may be observable. We employ Bloch oscillations as an interferometric tool to assess the role quantum fluctuations play in an array of quasi-two-dimensional Bose-Einstein condensates. Long-lived oscillations are observed when the chemical potential is balanced between sites, in a region where a macrodroplet is extended over several lattice sites. Further, we observe a transition to a state that is localized to a single lattice plane−driven purely by interactions−marked by the disappearance of the interference pattern in the momentum distribution. To describe our observations, we develop a discrete one-dimensional extended Gross-Pitaevskii theory, including quantum fluctuations and a variational approach for the on-site wavefunction. This model is in quantitative agreement with the experiment, revealing the existence of single and multisite macrodroplets, and signatures of a two-dimensional bright soliton.
M. Norcia, E. Poli, C. Politi, L. Klaus, T. Bland, M. J. Mark, L. Santos, R. N. Bisset, F. Ferlaino Can angular oscillations probe superfluidity in dipolar supersolids?, Phys. Rev. Lett. 129 40403 (2022-07-22), http://dx.doi.org/10.1103/PhysRevLett.129.040403 doi:10.1103/PhysRevLett.129.040403 (ID: 720697) Toggle Abstract
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.
T. Bland, E. Poli, C. Politi, L. Klaus, M. Norcia, F. Ferlaino, L. Santos, R. N. Bisset Two-Dimensional Supersolid Formation in Dipolar Condensates, Phys. Rev. Lett. 128 195302 (2022-05-13), http://dx.doi.org/10.1103/PhysRevLett.128.195302 doi:10.1103/PhysRevLett.128.195302 (ID: 720678)

Preprint

T. Bland, Elena Poli, Luis A. Peña Ardila, Luis Santos, F. Ferlaino, R. N. Bisset Domain supersolids in binary dipolar condensates, (2022-03-21), arXiv:2203.11119 arXiv:2203.11119 (ID: 720839) Toggle Abstract
Two-component dipolar condensates are now experimentally producible, and we theoretically investigate the nature of supersolidity in this system. We predict the existence of a binary supersolid state in which the two components form a series of alternating domains, producing an immiscible double supersolid. Remarkably, we find that a dipolar component can even induce supersolidity in a nondipolar component. In stark contrast to single-component supersolids, the number of crystal sites is not strictly limited by the condensate populations, and the density is hence substantially lower. Our results are applicable to a wide range of dipole moment combinations, marking an important step towards long-lived bulk-supersolidity.

2021

Article

E. Poli, T. Bland, C. Politi, L. Klaus, M. Norcia, F. Ferlaino, R. N. Bisset, L. Santos Maintaining supersolidity in one and two dimensions, Phys. Rev. A 104 63307 (2021-12-09), http://dx.doi.org/10.1103/PhysRevA.104.063307 doi:10.1103/PhysRevA.104.063307 (ID: 720729) Toggle Abstract
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.

Invited Talk

T. Bland Two dimensional supersolidity in a circular trap, UKFluids Network (Online) URL (2021-07-13), (ID: 720768)

Poster

T. Bland Controlled persistent current transport between toroidal quantum gases, Atomtronics@AbuDhabi2021 (Online, 2021-05-31) URL (2021-06-05), (ID: 720765)

Talks

T. Bland Formation of a two-dimensional supersolid, Interdisciplinary Workshop on Supersolidity (Trento, 2021-09-20) URL (2021-09-21), (ID: 720764)
T. Bland Two dimensional supersolidity in a circular trap, QuAMP 2021 (Online, 2021-08-31) URL (2021-09-02), (ID: 720767)