Gabriel G. Luther

Practical Free-Space Quantum Key Distribution over 1 km

A working free-space quantum key distribution system has been developed and tested over an outdoor optical path of {approximately}1 km at Los Alamos National Laboratory under nighttime conditions. Results show that free-space quantum key distribution can provide secure real-time key distribution between parties who have a need to communicate secretly. Finally, we examine the feasibility of surface to satellite quantum key distribution. {copyright} {ital 1998} {ital The American Physical Society}

Free-space quantum-key distribution

Nonproliferation and International Security,Los Alamos, NM 87545(February 1, 2008)A working free-space quantum key distribution (QKD)system has been developed and tested over a 205-m indooroptical path at Los Alamos National Laboratory under fluo-rescent lighting conditions. Resultsshow that free-space QKDcan provide secure real-time key distribution between partieswho have a need to communicate secretly.PACS Numbers: 42.79.Sz, 03.65-w

Solitary-wave solutions of the generalised three-wave and four-wave equations

Abstract The standard three-wave and four-wave equations are generalised by the inclusion of all resonant third-order nonlinearities. These generalised equations can be derived from an averaged lagrangian density. Analytic solitary-wave solutions of the governing equations are obtained and the physical properties of the solitary waves are discussed.

A MICROWAVE INTERFEROMETER TO MEASURE PARTICLE AND SHOCK VELOCITIES SIMULTANEOUSLY

A microwave interferometric technique has been developed which measures the particle velocity, the shock velocity and gives information as to the index of refraction of the shocked material. The system has been tested at X-band from 40 to 300 kBAR. Experiments are underway to extend the frequency into the K-band and the pressure range to 600 kBAR. The apparatus will be described and data presented.

Geophysical tests of the gravitational red shift and ether drift

Abstract A conceptually simple earth-based experiment is proposed for measuring the gravitational red shift to a precision of 5 × 10 −5 and for measuring the ether drift to a precision approaching 1 × 10 −7 by placing synchronous atomic clocks at the top of Mt. Chimborazo in Ecuador, at sea level in Ecuador, at the bottom of the Ecuadorian trench, at sea level at the north pole, and at the bottom of and at the surface above the Mariana trench. The experiment is designed to measure the decoupled effects of both the gravitational red shift and ether drift components of time dilation. Using present technology, such a measurement would provide a factor of 3.4 increased precision over previous measurements of the gravitational ref shift and would stand alone as a precise test of the isotropy of space, interpreted as ether drift, on a geophysical scale.

Microwave interferometry to elucidate shock properties

A series of measurement have been performed using a simple, lightweight, inexpensive, compact K‐Band (SLICK) interferometer to measure the shock properties of passive (Teflon, grout) and energetic (HE) materials. Shock and particle velocity measurements are made simultaneously along the same path. This path is determined by either a thin walled (1/2 mil aluminum foil) waveguide embedded in the material or the caustic of a Teflon axicon. Typically the velocities are determined to about a percent. The measurements will be described and a data presented.

Practical quantum cryptography in free space

We demonstrated quantum cryptography, or quantum key distribution (QKD), in free space over an outdoor optical path of /spl sim/950 m under nighttime conditions. The success of free space QKD against a high background depends on the transmission and detection of single photons through an optically thick and turbulent medium. It has been shown that a combination of sub-nanosecond timing, narrow filters, spatial filtering, and adaptive optics can render the difficult detection problem tractable. Further, the nonbirefringent nature of the atmosphere at optical wavelengths allows the transmission of the single photon polarization states used in the free-space QKD protocol.

Free-space quantum key distribution at night

An experimental free-space quantum key distribution (QKD) system has been tested over an outdoor optical path of approximately 1 km under nighttime conditions at Los Alamos National Laboratory. This system employs the Bennett 92 protocol; here we give a brief overview of this protocol, and describe our experimental implementation of it. An analysis of the system efficiency is presented as well as a description of our error detection protocol, which employs a 2D parity check scheme. Finally, the susceptibility of this system to eavesdropping by various techniques is determined, and the effectiveness of privacy amplification procedures is discussed. Our conclusions are that free-space QKD is both effective and secure; possible applications include the rekeying of satellites in low earth orbit.