Realization of collective strong coupling with ion Coulomb crystals in an optical cavity

Optically induced structural phase transitions in ion Coulomb crystals

“…Ty, 37.10.Vz, 64.70.kp, 36.40.Ei When an ensemble of confined ions with the same sign of charge is cooled to a sufficiently low temperature, the ionic system forms a crystalline structure [1], often referred to as an ion Coulomb crystal. Since the first experimental realizations of ion Coulomb crystals through laser cooling of atomic ions into the milli-Kelvin regime in electromagnetic traps [2,3], there has been growing theoretical [4][5][6][7][8][9][10][11][12][13][14] and experimental [15][16][17][18][19][20][21][22][23][24] interest in studying the structural and dynamic properties of these crystals under different trapping conditions and for various ion compositions.The unique localization and isolation of the individual ions constituting the crystals have already led to a large number of amazing results within precision measurements [25], cavity quantum electrodynamics (CQED) [26][27][28][29][30], quantum information science [31][32][33][34][35], and cold molecular science [36][37][38][39]. For experiments involving larger three-dimensional ion Coulomb crystals, such as CQED related experiments [26,27] with the interesting prospect of creating quantum memories and other quantum devices, ...…”

“…The unique localization and isolation of the individual ions constituting the crystals have already led to a large number of amazing results within precision measurements [25], cavity quantum electrodynamics (CQED) [26][27][28][29][30], quantum information science [31][32][33][34][35], and cold molecular science [36][37][38][39]. For experiments involving larger three-dimensional ion Coulomb crystals, such as CQED related experiments [26,27] with the interesting prospect of creating quantum memories and other quantum devices, full structural control of the crystal structures is still in need for optimizing the coupling between the ions and the cavity modes.…”

“…For experiments involving larger three-dimensional ion Coulomb crystals, such as CQED related experiments [26,27] with the interesting prospect of creating quantum memories and other quantum devices, full structural control of the crystal structures is still in need for optimizing the coupling between the ions and the cavity modes.…”

“…For medium sized crystals often employed in experiments [26,27] (∼ 10 3 − 10 5 ions), the structure is generally not very stable, and thermally induced transitions between a large variety of states including metastable bcc and fcc structures and incommensurable crystallite formations can be observed [40,41]. While structural stability can be dramatically increased using two-species crystals [21,23], means to control and manipulate the structures of single-species crystals are highly wanted, not only for applications in quantum information science, but also for exploiting Coulomb crystals as simulators of solid state physics, like structural transitions of iron under extreme pressure [42] of relevance for geophysics and thin-film growth [43] of importance for nanotechnology.…”

“…In order to freely adjust the standing wave period for a given near resonant laser frequency, the crystal can be trapped in the region where two beams of a bow tie ring cavity cross [50]. Alternatively, a practically simpler solution may be to employ a linear optical cavity along the rf field free axis of a linear rf trap, as in recent experiments [26,27], and tune the ion density such that the periodicity of the relevant lattice planes of the fcc and bcc structures becomes an integer multiple of half the wavelength of the light field. We have checked by MD simulations that the transfer works as well in this scenario.…”