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PubMed2003

Violation of Bell's inequality with photons from independent sources.

We report a violation of Bell's inequality using one photon from a parametric down-conversion source and a second photon from an attenuated laser beam. The two photons were entangled at a beam splitter using the postselection technique of Shih and Alley [Phys. Rev. Lett. 61, 2921 (1988)]]. A quantum interference pattern with a visibility of 91% was obtained using the photons from these independent sources, as compared with a visibility of 99.4% using two photons from a central parametric down-conversion source.

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PubMed2002

High-fidelity quantum logic operations using linear optical elements.

Knill, Laflamme, and Milburn [Nature (London) 409, 46 ((2001))]] have shown that quantum logic operations can be performed using linear optical elements and additional ancilla photons. Their approach is probabilistic in the sense that the logic devices fail to produce an output with a failure rate that scales as 1/n, where n is the number of ancilla. Here we present an alternative approach in which the logic devices always produce an output with an intrinsic error rate that scales as 1/n(2), which may have several advantages in quantum computing applications.

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PubMed2002

Demonstration of nondeterministic quantum logic operations using linear optical elements.

Knill, Laflamme, and Milburn [Nature (London) 409, 46 (2001)] recently showed that nondeterministic quantum logic operations could be performed using linear optical elements, additional photons (ancilla), and postselection based on the output of single-photon detectors. Here we report the experimental demonstration of two logic devices of this kind, a destructive controlled-NOT (CNOT) gate and a quantum parity check. These two devices can be combined with a pair of entangled photons to implement a conventional (nondestructive) CNOT that succeeds with a probability of 1/4.

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PubMed2002

Strategy for the treatment of noncompliant hypertensive hemodialysis patients.

Hypertensive hemodialysis patients noncompliant for their medications do not benefit from pharmacologic advances in the treatment of high blood pressure, and increase their already high risk of cardiovascular complications. The medical staff often becomes frustrated by severe hypertension in those who refuse to take medicines at home, drink excessive fluids, miss multiple dialysis sessions and sign-off dialysis early. In addition to addressing the psychosocial, financial, educational and substance abuse problems which contribute to noncompliance, we have developed a medication strategy to serve as an at least interim means of lowering blood pressure. Antihypertensive agents which have long half-lives in renal failure (lisinopril) and/or are intrinsically long acting (transdermal clonidine and amlodipine) were administered on dialysis days by the unit personnel to those patients who did not or would not take that or any dose on their own. The lisinopril and amlodipine were assured to have been taken on at least the dialysis days (thrice weekly), and the clonidine patch replaced weekly. Sixteen patients were thus treated when they failed to reliably self-administer medications. They had a significant decline in the predialysis systolic pressure of 15 mm Hg (175 +/- 6 to 160 +/- 5 mm Hg), diastolic of 12 mm Hg (103 +/- 3 to 91 +/- 3 mm Hg), and mean pressure of 13 mm Hg (127 +/- 4 to 114 +/- 4 mm Hg). There was an improvement in post-dialysis bood pressures, with the mean pressure declining 13 mm Hg from 110 +/- 4 to 97 +/- 4 mm Hg. Many individuals had erratic blood pressure control, having intermittently missed dialysis and hence unit-administered medicine, as well as continued fluid or drug abuse. The patients had uniformly excellent acceptance of this regimen, even spontaneously requesting it, and had no appreciable adverse effects. In summary while noncompliance is being addressed by the entire medical team, dialysis unit administration of long-acting medicines helps many hypertensive dialysis patients who would otherwise be at increased risk for severe cardiovascular complications.

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