AAWSAP DIRD, Concepts for Extracting Energy from the Quantum Vacuum, April 2010

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Brane or "brane world") analogs of the Casimir effect yet to be explored . But a detailed
consideration of these is beyond the scope of this report and will be left for future
investigation.
Squeezed Quantum Vacuum
It was discovered in 1965 that quantum field theory has the remarkable property of
allowing states of matter containing local regions of negative (vacuum state) energy
density or negative fluxes (Reference 94). In general, the local (vacuum state) energy
density in quantum field theory can be negative due to quantum coherence effects
(Reference 94). A primary byproduct of this discovery is the "squeezed quantum
vacuum," which later gave rise to new phenomenon such as the gravitationally
squeezed vacuum discussed previously. Substantial theoretical and experimental work
has shown that in many quantum systems the limits to measurement precision imposed
by the quantum vacuum ZPF can be breached by decreasing the noise in one
observable (or measurable quantity) at the expense of increasing the noise in the
conjugate observable; at the same time the variations in the first observable, say the
energy, are reduced below the ZPF such that the energy becomes "negative."
"Squeezing" is thus the control of quantum fluctuations and corresponding
uncertainties, whereby one can squeeze/reduce the variance of one (physically
important) observable quantity provided the variance in the (physically unimportant)
conjugate variable is stretched/increased. The squeezed quantity possesses an
unusually low variance, meaning less variance than would be expected on the basis of
the equipartition theorem. One can in principle exploit quantum squeezing to extract
energy from one place in the ordinary vacuum at the expense of accumulating excess
energy elsewhere.
The squeezed state of the electromagnetic field is a primary example of a quantum field
that has negative energy density and negative energy flux. Such a state became a
physical reality in the laboratory as a result of the nonlinear-optics technique of
"squeezing"; that is, of moving some of the quantum-fluctuations of laser light out of
the cos[w(t - z/c)] part of the beam and into the sin[ro(t - z/c)] part (Reference 95­
100). 16 The observable that gets squeezed will have its fluctuations reduced below the
vacuum ZPF. The act of squeezing transforms the phase space circular noise profile
characteristic of the vacuum into an ellipse, whose semimajor and semiminor axes are
given by unequal quadrature uncertainties (of the quantized electromagnetic field
harmonic oscillator operators). This applies to coherent states in general, and the usual
vacuum is also a coherent state with eigenvalue zero. As this ellipse rotates about the
origin with angular frequency, ro, these unequal quadrature uncertainties manifest
themselves in the electromagnetic field oscillator energy by periodic occurrences, which
are separated by one quarter cycle, of both smaller and larger fluctuations compared to
the unsqueezed vacuum.
Caves (Reference 101) points out that if one squeezes the vacuum-that is, if one puts
vacuum rather than laser light into the input port of a squeezing device-then one gets
at the output an electromagnetic field with weaker fluctuations and thus less energy
density than the vacuum at locations where cos2[ro(t - z/c)] =1 and sin 2[ro(t - z/c)] < <
1; but with greater fluctuations and thus greater energy density than the vacuum at
locations where cos2[ro(t - z/c)] << 1 and sin 2[ro(t - z/c)] =1. Since the vacuum is
16 w is the angular frequency of light, tis time, and z denotes the z-axis direction of beam propagation.
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