Quantum Information Related Optics Research @ UBC Physics and Astronomy

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Quantum Information Related Optics Research _at_ UBC
Physics and Astronomy

• Jeff Young et al.
• Kirk Madison et al.
• David Jones et al.

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Three Principal Areas

• Optical lattices (Kirk Madison)
• Simulating complex quantum problems
• Photonic crystal/quantum dot-based nonlinear
  optics (Jeff Young)
• Towards QED on-a-chip
• Phase-controlled laser sources (David Jones)
• Coherent control

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Quantum materials research with ultra-cold atomic
gases
Kirk Madison
Theme An ensemble of ultra-cold atoms held in
optical potentials can be used to experimentally
realize and study certain model
Hamiltonians Directions Realize N-body quantum
systems of fundamental interest to condensed
matter physics - low dimensional and/or strongly
correlated systems - examples include 1-D
chains - (Luttinger liquids and Tonks gas)
2-D and 3-D Hubbard (lattice) models with
bosons and/or fermions Goal study the
behavior of various model Hamiltonians to
determine the essential ingredients (terms in
H) of new and/or unexplained phenomena - examples
include high-Tc superconductivity
proof of principle recent experimental
realization of the Bose-Hubbard model
What is its connection (if any) to the
Fermi-Hubbard model?
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Periodic optical potentials are the analog of
ionic crystal potentials
- the optical-dipole potential experienced by an
atom (AC stark shift) is proportional to the
laser intensity - an intensity standing wave can
be made by interfering two monochromatic lasers
Designer Potentials
the depth (intensity), position (phase), and
periodicity (wave vectors) of the potential can
be controlled by changing the properties of the
interfering beams the topography can also be
changed by adding more beams linear gradients
can be added using external fields
(gravitational, magnetic)
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The connection to electronic condensed matter
systems is by analogy
analogous to
electron
atom
optical lattice
ionic crystal
collisional interaction
Coulomb interaction
spatial rotations
magnetic fields
in some cases
Notable differences
optical lattices possess (almost) perfect
crystal order no phonons, no impuries, no
dislocations but imperfections can be added
in... the atoms considered here are
neutral but mass equivalent to charge d.o.f.
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The connection to theoretical model systems is
more direct
proof of principle recent experimental
realization of the Bose-Hubbard model
Greiner, Mandel, Esslinger, Haensch, and
Bloch Quantum phase transition from a superfluid
to a Mott insulator in a gas of ultracold atoms,
Nature 415, 39 (2002)
new and relevant proposals to observe other
effects with cold atoms abound
Hofstetter, Cirac, Zoller, Demler, and
Lukin High-Temperature Superfluidity of
Fermionic Atoms in Optical Lattices, Phys. Rev.
Lett. 89, 220407 (2002)
A major contribution that experiments with
ultra-cold atomic gases could make is to bridge
the gap between models and real materials
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Integrated (Nonlinear) Optical Circuits

• Based on highly-evolved silicon-on-insulator and
  III-V semiconductor wafer processing technology
  (optical steppers, tight tolerances)
• High-Q, ultra small volume microcavities defined
  by lithography and etching (ie. engineerable)
• Integrate with artificial quantum dots to achieve
  nonlinear optics at the single photon level

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Ideal Design Scenario
PC Inside
Cavity
Bend
I/O Coupler
Optical Transistor
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SOI Sample Geometry
100 fs OPO
(200 nm x 450 nm Si channels)
Galian Photonics Inc.
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Nanostructured Microcavity embedded in Single
Mode SOI Waveguide
Cowan, Rieger and Young, Optics Express (in press)
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3D Microcavities in Waveguides
Q 250
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Add PbSe Quantum Dots to Enhance Nonlinear
Susceptibility in Cavity
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Soon to be Integrated
Murray McCutcheon, in progress
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Close Up
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Q10,000
FDTD
Greens Function
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Minimize Switching Power Using 1D Waveguide
Nonlinear 0D Defect Cavity
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Lorentzian Bistability (no background)
lb2/n2 0, 0.1 0.4
Soljacic et al., PRE 66, 055601(R) 2002 Cowan and
Young, PRE 68, 46606, 2003
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Nonlinear Cavity Effect with QDots
Q1200
Pumped on resonance
Transmission (a.u.)
Pumped off resonance
Energy (cm-1)
Cowan, in progress
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Optical Waveform Synthesis (David Jones)

• Phase-stabilized fs lasers are used to engineer
  coherent electric field waveforms at optical
  (300-600 THz) frequencies with well-defined
  optical phases
• Controlling the carrier-envelope phase (fCE)
• Combined with pulse shaping techniques
• Leads to

f
CE
f
f
f
f
lens
lens
grating
grating
spatial light modulator (SLM)
input pulse
shaped pulse
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LUX - Laser Systems
Laser-based timing system - femtosecond x-ray
pulses derived from laser pulses or
laser-based RF Interconnected femtosecond laser
systems - actively synched or seeded from
master Maintain lt100 fs synchronization -
laser to laser synchronization - stabilized
timing distribution network
Master Oscillator Laser RF
HGHG FEL Seed Laser
distribution network
crab cavity
Photo Injector Laser
Multiple Beamline Endstation Lasers
LINAC RF
R. Schoenlein LUX Review 4/28/03
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Summary

• UBC Physics and Astronomy has a number of optical
  research activities that are directly relevant to
  quantum information technologies

Acknowledgements NSERC, CIAR, Galian Photonics
Inc., CFI, BCKDF
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Spectra 800 mm Long Single Mode
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201 Negative Differential Transmission Using
In-line Filter
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Distribution of Time/Frequency Standards
Time/frequency ?
Plentywood
Known time/frequency

• How do you compare time/frequency?
• Transport clock
• via GPS/ two way satellite transfer
• optical fiber link
• Motivation for high stability time/frequency
  transfer
• Comparison of optical standards for fundamental
  physics,
• Remote pulse synchronization Laser and Linac
  http//bc1.lbl.gov/CBP_pages/CBP/groups/LUX/
• Surveillance
• Telecom network synchronization

Increase in stability