Historical research guide · 0075 · 2011
DIRD Quantum Tomography of Negative Energy States in the Vacuum
DIA / AAWSAP contractor
In one minute
This is the Defense Intelligence Agency report on how you would actually measure negative energy — the ingredient a warp drive or a traversable wormhole needs. Its opening line is unhedged: future aerospace vehicles could carry a propulsion system that uses negative quantum vacuum energy to reshape the spacetime around the craft. The author’s argument is that we already make negative energy in two ways in the laboratory, in a Casimir cavity and in squeezed light, and that before anyone tries to make more of it, we need instruments that can see where it is. The tool he proposes is quantum optical homodyne tomography: pairs of photodiodes that subtract their outputs and read the fluctuations of the electric field itself, one phase angle at a time, until the quantum state can be reconstructed like a CT scan. He then recommends building portable versions — both to map the field around an engineered spacetime, and, in arrays, to detect craft already using one.
Connection
Chapter 4 turns on whether exotic matter is a real laboratory substance or a mathematical excuse, and this DIA report answers plainly: negative energy is made in the lab today, the general-relativistic energy conditions that appear to forbid it are hypotheses rather than laws, and here is the instrument that would map it. It is also the measurement side of chapter 6’s Casimir programme — Marecki’s detector reads the vacuum inside a Casimir cavity directly rather than inferring it from the force.
From the source
Small amounts of negative (sub-vacuum) energy density are already produced in the laboratory by two known routes — the static Casimir effect and time-domain squeezed states of the electromagnetic field — and a squeezed vacuum is a travelling wave that oscillates between negative and positive energy density while keeping a positive time-averaged energy density.Introduction, p. 1; Negative (Sub-Vacuum) Energy in Squeezed Light, pp. 8-12
The general-relativistic energy conditions are mathematical hypotheses rather than laws: quantum field theory allows local regions of negative energy density, the energy conditions have been experimentally shown to be false, and Visser showed that all generic spacetime geometries violate all of them — so the objection that faster-than-light and antigravity spacetimes are implausible because exotic matter violates the energy conditions is a spurious issue.Review of Negative (or Sub-Vacuum) Energy, Overview, pp. 3-4
Balanced homodyne detectors with local oscillators are amplifiers capable of measuring the one- and two-point functions of arbitrary quantum field states, including the vacuum itself; the pulsed time-domain detector of Hansen and colleagues reconstructed the Wigner function and density matrix of a coherent state with 99.5 percent fidelity at 91 percent quantum efficiency, resolving individual laser pulses at up to 1 MHz.Time-Domain Balanced Homodyne System, pp. 33-35
Marecki’s modified balanced homodyne detector, placed inside a Casimir cavity with plates 1 micrometre apart, submicrometre photodiodes and the cavity’s own TE1 mode serving as the local oscillator, would directly detect and spatially map the sub-vacuum fluctuations and the negative energy density inside — a tomography of the ground state of the Casimir cavity, revealing much finer detail than the already-measured Casimir force.Balanced Homodyne System for Casimir Cavities, pp. 36-42
The predicted spectral density inside the cavity is static and in some regions corresponds to a suppression of vacuum fluctuations by at least 3 dB, which the Quantum Inequalities theorem allegedly forbids; Marecki finds that the static negative energy density inside a Casimir cavity violates that theorem, so the proposed experiment is also a test of whether sub-vacuum energy can persist.Balanced Homodyne System for Casimir Cavities, pp. 42-43; Conclusion, p. 44
The report recommends a research and development programme to modify, develop and commercialise portable time-domain and modified-Marecki homodyne detectors, both to map the negative energy produced by a pulsed or static negative-energy generator engineering the spacetime around an aerospace platform, and, assembled into sensor arrays, for surveillance and detection of anomalous aerospace platforms that might already use engineered spacetime effects for propulsion.Conclusion, pp. 43-44
The way in
https://documents2.theblackvault.com/documents/dia/AAWSAP-DIRDs/DIRD_36-DIRD_Quantum_Tomography_of_Negative_Energy_States_in_the_Vacuum.pdfHow to cite it
DIA / AAWSAP contractor (2011) DIRD Quantum Tomography of Negative Energy States in the Vacuum https://documents2.theblackvault.com/documents/dia/AAWSAP-DIRDs/DIRD_36-DIRD_Quantum_Tomography_of_Negative_Energy_States_in_the_Vacuum.pdf