Studying The Properties Of SF6 Gas Mixtures For Directional Dark Matter Detection

Although dark matter comprises approximately 85\% of the matter content of the universe, direct detection of dark matter remains elusive. As the available parameter space for dark matter candidates is pushed to lower and lower limits, the demand for larger, more sensitive detectors continues to grow. Although upscaling the detector improves the sensitivity, it greatly increases the cost and complexity of the experiment. Even after a dark matter signal is detected, there remains the possibility that an unknown background mimics the dark matter signal. Consequently, verifying the dark matter origin of a detection signal is an issue for any dark matter experiment. The solution is to search for the so-called ``smoking gun signatures for dark matter. There is the annual modulation of the event rate, and the modulation of the recoil direction over a sidereal day. The directional modulation is the more robust signal. It would not only unambiguously confirm the existence of dark matter, but pave the way for characterizing the properties of dark matter. This thesis describes research toward advancing low pressure gas Time Projection Chamber (TPC) technology for directional dark matter detection. It begins by measuring the thermal negative ion behavior of the novel TPC gas, SF6, and thereby confirming SF6 as an ideal gas for directional dark matter experiments. The disadvantage of SF6 is the low fiducialization efficiency due to the relatively small secondary drift species, SF5-. This motivated studies of CF4-SF6 gas mixtures that led to the discovery of a new negative ion species hypothesized to be CF3-. We show that the relative production of the new species can be tuned by adjusting the SF6 concentration and the drift field. We also propose a model for CF3- production in CF4-SF6 gas mixtures that makes qualitative predictions, which are consistent with our measurements. Our studies show that a 20-3 CF4-SF6 mixture results in low thermal diffusion and a factor two enhancement of the fiducialization efficiency relative to that measured for pure SF6. Using this mixture our measurements demonstrate gamma/electron discrimination down to 15 keVee and head-tail directionality down to 30 keVee. These are the first such measurements in TPCs with SF6-based gases, and the first utilizing a 1D readout in any gas

Quantum time transfer for freespace quantum networking

Timing requirements for long-range quantum networking are driven by the necessity of synchronizing the arrival of photons, from independent sources, for Bell-state measurements. Thus, characteristics such as repetition rate and pulse duration influence the precision required to enable quantum networking tasks such as teleportation and entanglement swapping. Some solutions have been proposed utilizing classical laser pulses, frequency combs, and bi-photon sources. In this article, we explore the utility of the latter method since it is based upon quantum phenomena, which makes it naturally covert, and potentially quantum secure. Furthermore, it relies on relatively low technology quantum-photon sources and detection equipment, but provides picosecond timing precision even under high loss and high noise channel conditions representative of daytime space-Earth links. Therefore, this method is potentially relevant for daytime space-Earth quantum networking and/or providing high-precision secure timing in GPS denied environments

Two-Way Quantum Time Transfer: A Method for Daytime Space-Earth Links

Remote clock synchronization is crucial for many classical and quantum network applications. Current state-of-the-art remote clock synchronization techniques achieve femtosecond-scale clock stability utilizing frequency combs, which are supplementary to quantum-networking hardware. Demonstrating an alternative, we synchronize two remote clocks across our freespace testbed using a method called two-way quantum time transfer (QTT). In one second we reach picosecond-scale timing precision under very lossy and noisy channel conditions representative of daytime space-Earth links with commercial off-the-shelf quantum-photon sources and detection equipment. This work demonstrates how QTT is potentially relevant for daytime space-Earth quantum networking and/or providing high-precision secure timing in GPS-denied environments.Comment: arXiv admin note: text overlap with arXiv:2211.0073