Dr. Howard E. Brandt U.S. Army Research Laboratory (ARL)

An Isaac Newton Institute WorkshopEntanglement and Transfer of Quantum

Information

Quantum Cryptographic Probing by Entanglement

27 September – 1 October 2004

u 1=

v 0=

v 1=

u 0=

Binary Encoding in Photon Linear-Polarization States

for BB84 Protocol

1e

0e

General Entangling Probe

Probe interacts unitarily with signal on its way from

transmitter to legitimate receiver and is projectively measured

after signal is projectively measured by legitimate receiver.

M

ProbeMeasuring

Device

Probe

Transmitter

Receiver

U

(two-dimensional probe)

(four-dimensional probe)

(four-dimensional probe)

Entangling Probe Schematic

CNOT gate(cavity QED /

solid state / ?)

probe photon

incident signal state

gated probe photon

gated signal photon

delay switch

WollastonPrism

H. E. Brandt, “Optimum probe parameters for entangling probe in quantum key distribution,” Quantum Information Processing 2, 37-79 (2003).

H. E. Brandt, “Optimization problem in quantum cryptography,” J. Optics B 5, S1-4 (2003).

H. E. Brandt, “Quantum measurement with a positive operator valued measure”, J. Optics B 5, S266-270 (2003). H. E. Brandt, “Probe optimization in four-state protocol of quantum cryptography,” Phys. Rev. A 66, 032303 (16) (2002). H. E. Brandt, “Secrecy capacity in the four-state protocol of quantum key distribution,” J. Math. Phys. 43, 4526-4530 (2002). H. E. Brandt, “Inconclusive rate with a positive operator valued measure,” Contemp. Math. 305, 43-52 (2002). H. E. Brandt, “Qubit Devices,” Proc. Sympos. Appl. Math. 58, 67-139 (2002). H. E. Brandt, “Deconstructing Wigner’s density matrix concerning the mind-body question,” Found. Phys. Lett. 15, 287-292 (2002).

Selected Refereed Publications on Quantum Information Processing

 H. E. Brandt, “Inconclusive rate in quantum key distribution,” Phys. Rev. A 64, 042316 (5) (2001). H. E. Brandt, “Inconclusive rate as a disturbance measure in quantum cryptography,” Phys. Rev. A 62, 042310 (14) (2000). H. E. Brandt, “Eavesdropping optimization for quantum cryptography using a positive operator-valued measure,” Phys. Rev. A 59, 2665-2669 (1999). H. E. Brandt, “Positive operator valued measure in quantum information processing,” Am. J. Phys. 67, 434-439 (1999). H. E. Brandt, “Qubit devices and the issue of quantum decoherence,” Prog. Quantum Electronics 22, 257-370 (1998). H. E. Brandt, “Quantum decoherence in qubit devices,” Opt. Eng. 37, 600-609 (1998). H. E. Brandt, J. Myers, S. Lomonaco, “Aspects of entangled translucent eavesdropping in quantum cryptography,” Phys. Rev. A 56, 4456-4465 (1997). J. Myers, H. E. Brandt, “Converting a positive operator-valued measure to a design for a measuring instrument on the laboratory bench,” Meas. Sci. Technol. 8, 1222-1227 (1997).

Selected Refereed Publications on Quantum Information Processing (cont.)