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A quantum optical beam. Classically an optical beam can have well defined amplitude AND phase simultaneously. Quantum mechanics however imposes an uncertainty principle. The deterministic classical beam is blurred out by quantum noise. Uncertainty principle:.

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Presentation Transcript
a quantum optical beam
A quantum optical beam
  • Classically an optical beam can have well defined amplitude AND phase simultaneously.
  • Quantum mechanics however imposes an uncertainty principle.
    • The deterministic classical beam is blurred out by quantum noise.

Uncertainty principle:

coherent state squeezed state
Coherent state Squeezed state
  • V+=V-=1
  • Ideal output of a low-noise laser
  • Same quantum noise as vacuum
  • V+ or V- < 1
  • Very fragile in the presence of loss
sideband squeezing
Sideband squeezing
  • Laser outputs are typically very noisy at low frequency.
  • Measure squeezing of the beat of the carrier with frequencies outside this noise bandwidth.
production of squeezing

Coherent

Production of squeezing
  • Produce squeezing in a below threshold optical parametric amplifier (OPA)
production of squeezing1

Amplitude squeezed

Coherent

Production of squeezing
  • Produce squeezing in a below threshold optical parametric amplifier (OPA)
production of squeezing2

Amplitude squeezed

Phase squeezed

Coherent

Production of squeezing
  • Produce squeezing in a below threshold optical parametric amplifier (OPA)
comparison of opas and opos
Comparison of OPAs and OPOs
  • OPAs are seeded with a bright beam whereas OPOs are vacuum seeded.
  • Advantages of OPAs:
    • Can lock the length of the resonator.
    • Bright squeezed output that can be controlled in downstream applications.
  • Advantage of OPOs:
    • No classical noise coupled from the laser into the squeezed beam.
slide9

Recovering buried squeezing

  • In our two OPAs this noise is correlated and can be cancelled by optical or electronic means.
the poincar sphere2

Commutation relations

of Stokes operators

Uncertainty relations

of Stokes operators

The Poincaré sphere
the poincar sphere3

Commutation relations

of Stokes operators

Uncertainty relations

of Stokes operators

The Poincaré sphere
polarisation squeezing
Polarisation squeezing
  • A Stokes parameter is squeezed if its variance is below the shot-noise of a coherent beam of equal power.
slide17

one Stokes

parameter

squeezed

Polarisation state of an

amplitude squeezed beam

Polarisation state of a

coherent beam

slide18

one Stokes

parameter

squeezed

one Stokes

parameter

squeezed

Polarisation state of a

coherent beam

Polarisation state of an

amplitude squeezed beam

Polarisation state of a

squeezed beam combined

with a coherent beam

[P.Grangier et al., Phys.Rev.Lett, 59, 2153 (1987)]

slide19

one Stokes

parameter

squeezed

one Stokes

parameter

squeezed

one Stokes

parameter

squeezed

Polarisation state of two

phase squeezed beams

combined

Polarisation state of a

coherent beam

Polarisation state of an

amplitude squeezed beam

Polarisation state of a

squeezed beam combined

with a coherent beam

[P.Grangier et al., Phys.Rev.Lett, 59, 2153 (1987)]

slide20

one Stokes

parameter

squeezed

one Stokes

parameter

squeezed

one Stokes

parameter

squeezed

two Stokes

parameters

squeezed

Polarisation state of two

phase squeezed beams

combined

Polarisation state of two

amplitude squeezed

beams combined

Polarisation state of a

coherent beam

Polarisation state of an

amplitude squeezed beam

Polarisation state of a

squeezed beam combined

with a coherent beam

[W. Bowen et. al. http://xxx.lanl.gov/abs/quant-ph/0110129(2001)]

[P.Grangier et al., Phys.Rev.Lett, 59, 2153 (1987)]

slide22

OPA I

Squeezed beam II

Squeezed beam I

OPA II

summary
Summary
  • We have produced two reliable strongly quadrature squeezed sources.
  • We produce new quantum polarisation states and investigate their properties.
  • We cancel the classical noise of our input laser beam to produce squeezing at low frequencies.
  • We have produced EPR entanglement and are presently characterising it.