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This Defense Intelligence Reference Document from the Defense Intelligence Agency is dated 11 January 2011. It was produced in FY 2010 under the Advanced Aerospace Weapons System Applications (AAWSA) Program. It reviews negative, or sub-vacuum, energy found in squeezed light and the Casimir effect, and explains quantum optical homodyne tomography as a way to measure and map that energy in the lab. It proposes balanced homodyne detector arrays that could help detect anomalous aerospace platforms using engineered spacetime propulsion.
“Hansen”5 pages
signal a UNCLASSIFIED/ ff81il 8ffllil.t.k WE&i Qllk>C detector ~~~ local oscillator (o:LO) detector Figure 10. Schematic of a Balanced Homodyne Detector. (courtesy of Ulf Leonhardt) Furthermore, the balanced homodyne detector is also an amplifier. The LO amplifies the signal by the mutual optical mixing of the two. In other words, the homodyne detector is an interferometer that can be measurably imbalanced by a single photon in the signal mode because the reference field is very intense. A very important technical advantage of this is that the amplified signal is well above the electronic noise floor of the photodiodes. The signal amplitude is enhanced so that even the noisy linear- response photodiodes can detect the quantum features of the signal with single photon resolution. Because the LO serves as a coherent amplifier, it also chooses the signal mode. The LO singles out one spatial-temporal (bosonic) mode from the rest of the continuous quantum field "light" (that matches the LO field). In this way the observer separates the quantum object (a single optical mode) from the rest of the world. The mode function is given by the spatial-temporal shape of the LO beam at the detector surface and during the measurement time interval [O, n. The overall phase and intensity of the LO is comprised in the complex amplitude aLO. Shifting the phase 0 = arg(aw) rotates the measured ch1 . The observer defines via the LO the frame in space and time that is subject to the field-quadrature measurement. By tailoring the shape of the LO beam high spatial-temporal resolution can be achieved. Photodetection is usually not completely efficient in practice so it is important to describe the influence of inefficiencies on homodyne detection. This is easily done by using the simple model for losses in direct photodetection that was given in Section IIIB-2. We imagine fictitious beam splitters to be placed in front of the two (assumed ideal) detectors in the measurement setup (see Figure 11). We use 29 UNCLASSIFIED//FQII. QFFlliil,t.k Wliilii &nlk'f
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