coherent excitation of rydberg atoms on an atom chip
DESCRIPTION
Coherent excitation of Rydberg atoms on an atom chip. Rutger M. T. Thijssen Van der Waals - Zeeman Instituut voor Experimentele Natuurkunde. Quantum Information Processing. Qubits Coherence Switchable interactions Scalability. MAGCHIPS. “Atom chip” (room temperature). 22 µ m. - PowerPoint PPT PresentationTRANSCRIPT
Coherent excitation of Rydberg atoms on an atom chip
Rutger M. T. ThijssenVan der Waals - Zeeman Instituut voor
Experimentele Natuurkunde
Quantum Information Processing Qubits Coherence Switchable interactions Scalability
MAGCHIPS
MAGCHIPS Permanent magnetic lattice atom chip Gold-coated for laser cooling 500 populated magnetic microtraps
Prospective qubits 87Rb, T~mK
10 µm22 µm
Magnetised film
“Atom chip”(room temperature)
Neutral atoms: intrinsically weak interaction with environment Exquisite control & manipulation Scalability Stable qubits
Quantum information on MAGCHIPS
Neutral atoms: intrinsically weak interaction with environment Exquisite control & manipulation Scalability Stable qubits
Quantum information on MAGCHIPS
Intrinsically weak interaction with environment Good: long coherence times (~sec.) Challenge: quantum information requires interaction: we have to
work to add an interaction between qubits (i.e. traps)
Rydberg atoms Hydrogen-like atom High principal (n) quantum
number Large dipole-dipole interaction
between Rydberg atoms
Dipole blockade
32121 )ˆ)(ˆ(3
RRRV
mmmm
2nm
Rydberg Excitation
Toptica DL-100 diode laser (30mW)
Toptica TA-SHG 110 frequency doubled diode laser, tunable from 488-479nm (n=18-ionization threshold) (300mW)
|nd
|5s
|5p
780nm (infrared)
480nm (blue)
|ns
Electromagnetically Induced Transparency
|nd
Ec
ji ,m
ppc
pp i
L
12
22 244)(
|5s
|5p
Ωp
δωp
γ12
Detuning (δωp)
Electromagnetically Induced Transparency
|nd
Ec
ji ,m
ppc
pp i
L
12
22 244)(
|5s
|5p
Ωc
Ωp
δωp
γ12
Detuning (δωp)
Electromagnetically Induced Transparency – dressed states
|a+
780nm (infrared)
|a0 (5s)
|a-
Rediagonalise interaction Hamiltonian
Interference between |a+ and |a- dressed states: reduced probe absorption on two-photon resonance
|5s
|5p
|nd
Ωc
Ωp
Autler – Townes splitting + Fano interference
EIT – frequency stabilisation in a vapour cell
Coupling laser detuning (MHz)
vapour cell EIT, |39ddichroic mirror
dichroic mirror
Rubidium vapour cell
fast photodiode
780 nm diode laser
480 nm diode laser
EIT Imaging
optical fiber
EIT Imaging
optical fiber
Position (px)
Detu
ning
(MHz
)O
ptica
l den
sity
EIT Imaging Blue laser frequency locked to vapour cell EIT Red laser scanned over resonance
Surface effects• Near-field blackbody radiation from chip • “mirror” effect: Rydberg atom interacting with itself• Photoelectric effect on surface: adsorbed Rb, Au• Patch potentials
• Crystal defects in FePt• Adsorbed Rb ions
eV58.2/ hcE
Summary MAGCHIPS experiment Rydberg / EIT for interactions between qubits
Built laser system Built frequency locking setup for probe and coupling laser
Imaged Rydberg / EIT in surface magneto-optical trap
Investigating effects of surface on Rydberg levels Build a quantum computer…
Summary MAGCHIPS experiment Rydberg / EIT for interactions between qubits
Built laser system Built frequency locking setup for probe and coupling laser
Imaged Rydberg / EIT in surface magneto-optical trap
Investigating effects of surface on Rydberg levels Build a quantum computer…
2-photon gates Zoller Mesoscopic Rydberg gates using EIT
Rydberg interaction
|0> |1>
|0> |1>
Focused lasers
Ensemble A Ensemble B
Microwave/Raman6.8 GHz
Rydberg Atoms One highly excited
electron (n=20-100) Rydberg formula: Size ~ n^2 Lifetime ~ n^3 Polarisability ~n^7 Van der Waals
interaction ~ n^11 Dipole blockade shifts
nearby Rydberg levels
32121 )ˆ)(ˆ(3
RRRV
mmmm
2nm
2)( l
HB n
hcRE