1. A10 Designing spin-spin interactions in cold ion crystals
Rene Gerritsma, Ferdinand Schmidt-Kaler (Universität Mainz)
Planar Ion Trap
Probing atom-ion interactions
Techniques
Asymptotic states:
|nCOM, nstretch, natom
|001
|000
|100
|002
|101
|010
collision
laser
atoms
Glass chip with 50µm deep trenches to minimize stray fields from the substrate.
Trenches on the back side decrease the distance between the trap center and the source of the magnetic field. Simulations predict
a gradient up to 50T/m.
ion 2
ion 1
Analysis of atom-ion collisions via the Coulomb interaction between the
two ions followed by fluorescence state detection.
[1] Hempel, Lanyon, Jurcevic, Gerritsma, Blatt and Roos, Nature Phot. 7, 630 (2013).
[2] Kotler, Akerman, Navon, Glickman and Ozeri, Nature 510, 376 (2014).
[3] Schmidt-Kaler and Gerritsma, EPL 99, (2012). A3 A5
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Stable high current pulse
Ion controlled Josephson-Junction
We consider a setup in which atoms are trapped in an double-well potential with a trapped ion in between. By tuning the internal or motional state of the ion, the atomic tunnelling rate between the wells can be controlled [4,5].
Stable current pulses of 20A for a few milliseconds with a transistor circuit.
Heat from wires dissiplated into AlN substrate coupled to water cooling.
Integrated argon gun for in-situ cleaning of the surface, reported to reduce surface-induced ion heating rate [1]. 1) 1)
force
Future Goals 2) 2)
Short term goals:
Measurement of magnetic gradient with single-ion probe
Measurement of heating rate and surface cleaning
Observing mediated spin-spin coupling with a linear ion crystal
Mid term goals:
Scale up spin-spin interactions to two-dimensional ion crystals
Characterizing frustration effects in spin-spin interactions
Experimentally realizing spin-spin models such as the J1-J2 in ladder systems
Study spin-boson coupling along the Jahn-Teller dynamics[7]
Magnetic gradient B
(left) Spectrum of a double-well system for an inter-well separation of d = 2.5R* = 765 nm for 87Rb and 171Yb+ with
ωa = 2π 1.8 kHz and ωi = 2π 9.9 kHz. In the lower panel, the tunnelling rate is plotted.
(right) Corresponding probability distributions of the ion-atom states.
Paramagnetic linear ion crystal
Phase transition,
observed in radial
phonons when
increasing
the coupling
20 equidistant
spins
Jahn-Teller transition B
(left) The effect of micromotion: Spectrum for the groundstates of 7Li and 171Yb+ with ωa = 2π 1.8 kHz,
Ω = 2π 70.5 kHz for q = 0.4 and a = 0 such that ω i ≈ 2π 10 kHz. Energy crossings appear but avoided
crossings remain very small.
(right) Fidelity F(Ƭ) of the tunnelling dynamics for the atom-ion pair 87Rb / 171Yb+ at finite temperatures Ƭ.
anti-ferromag. ordering
Inhomogenious case:
ion crystal
[4] Joger, Negretti and Gerritsma, PRA 89, (2014).
[5] Gerritsma, Negretti, Doerk, Idziaszek, Calarco and Schmidt-Kaler PRL 109, (2012). A3 A5 A9
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coupling
strength g
Critical point
Long term goals:
Drive structural phase transitions and observe spin-driven quench dynamics
New trap with current wires included in a multi layer chip to minimize the distance to the trap center and further optimizing of the magnetic gradient
Observe the effect of impurities:
- local modes pinned to impurities
- modification of Kibble Zurek defect generation at impurity sites
Workplan
technology A8 B1
optimize trap control volt.
spin-spin
Surface cleaning
atom-ion
measure magn. gradient
trapping impurities
theory
Zigzag ion crystals
Theory for magnetic simulation S>1/2 [8]: magnetic field gradient in z-direction
Effective Hamiltonian after adiabatic ellimination
, m = projection of 50Mn+ – spin.
two ion spin-spin coupl.
Jahn Teller transition
Planar ion crystal spin-spin coupl.
Spin-induced struct. Phase transition
Field of activity for PhD I:
Operate planar ion trap with high magnetic gradient for spin-spin interaction
Hybrid trap characterization
BEC
Spin-motion coupling
atomic double well
Determine scattering rate
Raman laser
enhanced sensor
entangled ions
Field of activity for PhD II:
Operate hybrid trap for atom-ion interaction
heating/cooling rate
Polaron theory of ions in BEC
Quantum gate theory in ultra-cold bath
Year 1
Year 2
Year 3
Year 4
[6] N. Daniilidis et al., arXiv (2013)
[7] P. A. Ivanov et al., J. Phys. B 46, (2013)
[8] P. A. Ivanov et al., NJP 13, (2011) A3 A5
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Transregional Collaborative Research Centre SFB/TR 49
Frankfurt / Kaiserslautern / Mainz