Charles M. Simmons

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

The Los Alamos Trapped Ion Quantum Computer Experiment

The development and theory of an experiment to investigate quantum computation with trapped calcium ions is described. The ion trap, laser and ion requirements are determined, and the parameters required for quantum logic operations as well as simple quantum factoring are described.

Trapped Ion Quantum Computer Research at Los Alamos

We briefly review the development and theory of an experiment to investigate quantum computation with trapped calcium ions. The ion trap, laser and ion requirements are determined, and the parameters required for simple quantum logic operations are described. (LAUR 98-314).

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.

Progress Towards Using a Calcium Ion Trap to Perform Quantum Logic Operations

We briefly review the development and theory of an experiment to investigate quantum computation with trapped calcium ions. The ion trap, laser and ion requirements are determined, and the parameters required for simple quantum logic operations are described.

Circular format zig-zag scanning of vidicon tubes

In an effort to increase camera readout speed, we have developed a nonconventional vidicon tube scanning technique. Because all vidicon targets are round, acquiring a full view requires overscanning with a conventional square format scan, resulting in 22% of the video field time wasted. Furthermore, conventional scanning employs horizontal flyback, which for high frame rates can be more than 10% of the total field time. Our nonconventional scanning technique eliminates flyback time by utilizing a triangular waveform rather than a sawtooth for horizontal deflection. This triangle wave is amplitude modulated in order to scan only the (circular) area of interest. The vertical deflection is a staircase ramp, with a step occurring at the end of each horizontal line. This maintains even spacing and a parallel relationship between horizontal lines, as opposed to skewed lines with conventional scans. To display the video output, the X-Y monitor must also be driven with these waveforms in order to maintain the correct temporal and spatial position of the video data. Sweep rates of 400 lines in a 1 ms field have been demonstrated. Test results using this technique show a frame time reduction of approximately 30%, with no loss of resolution or dynamic range, and no increased video bandwidth requirements.