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. V + V − ≥1 Uncertainty principle:
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:. - PowerPoint PPT Presentation
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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.
V +V −≥1Uncertainty principle:
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
Laser outputs are typically very noisy at low frequency.
Measure squeezing of the beat of the carrier with frequencies outside this noise bandwidth.
Sideband squeezing
Coherent
Production of squeezing Produce squeezing in a below threshold
optical parametric amplifier (OPA)
Coherent
Production of squeezing Produce squeezing in a below threshold
optical parametric amplifier (OPA)
Amplitude squeezed
Coherent
Production of squeezing Produce squeezing in a below threshold
optical parametric amplifier (OPA)
Amplitude squeezedPhase squeezed
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.
In our two OPAs this noise is correlated and can be cancelled by optical or electronic means.
Recovering buried squeezing
(D,D )(H,V)
(L,R)
S0 =IH +I V
S1 =IH −IV
S2 =ID −ID
S3=IR −I L
The Poincaré sphere
(D,D )(H,V)
(L,R)
S0 =IH +I V
S1 =IH −IV
S2 =ID −ID
S3=IR −I L
The Poincaré sphere
ˆ S 1,ˆ S 2[ ]=2iˆ S 3
ˆ S 2,ˆ S 3[ ]=2iˆ S 1
ˆ S 3,ˆ S 1[ ]=2iˆ S 2
Commutation Commutation rrelationelationssoof f StokesStokes operators operators