US 2014/0177837 A1Published application

Method and Apparatus for Direct Counterfactual Quantum Communication

AssigneesKing Abdulaziz City for Science and Technology, The Texas A&M University System

InventorsMuhammad Suhail Zubairy, Zhenghong Li, Mohammad D. Al-Amri, Hatim A. Salih

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Abstract

It has long been assumed in physics that for information to travel in empty space between two parties (the Sender and the Receiver), “physically real” entities have to travel between the parties. The recently discovered technique of interaction-free measurement—wherein the presence of an object is inferred without the object directly interacting with the interrogating light—has caused this basic assumption to be questioned. This technique has found application in quantum key distribution in the form of counterfactual quantum key distribution albeit with limited efficiency. In the present invention, using the “chained” quantum Zeno effect, this logic is taken to its natural conclusion and, in the ideal limit, information can be transferred between the Sender and the Receiver without any physical particles whatsoever traveling between them.

Claims20

Dependent claims

A method for direct counterfactual quantum communication comprising:

(a) transmitting a photon in a first state to a first beam splitter that randomly causes the photon to take either a first path or a second path;
(b) randomly splitting a photon on the second path with a second beam splitter into a third path and a fourth path;
(c) selectively blocking photons on the fourth path;
(d) combining any photons on the third path with unblocked photons on the fourth path in a third beam splitter that passes photons into a fifth path and a sixth path such that, if constructive interference occurs, the probability of finding a photon on the sixth path is greater than if constructive interference does not occur;
(e) blocking photons on the sixth path if photons were blocked on the fourth path in step (c), above;
(f) combining any photons on the fifth path with unblocked photons on the sixth path in a fourth beam splitter that passes photons into a seventh path and an eighth path such that, if constructive interference occurs, the probability of finding a photon in the eighth path is greater than the probability of finding a photon in the sixth path and, if constructive interference does not occur, the probability of finding a photon in the eighth path is approximately equal to the probability of finding a photon in the sixth path;
(g) blocking photons on the eighth path if photons were blocked on the fourth path in step (c), above;
(h) combining any photons on the seventh path with unblocked photons on the eighth path in a fifth beam splitter that passes photons into a ninth path and a tenth path such that, if constructive interference occurs, the probability of finding a photon in the tenth path is equal to the probability finding a photon in the second path;
(i) detecting any photons on the tenth path;
(j) combining any photons on the ninth path with photons on the first path in a sixth beam splitter that passes photons into an eleventh path and a twelfth path such that, if constructive interference occurs, the probability of finding a photon in the twelfth path is greater than if constructive interference does not occur;
(k) repeating steps (b) through (i), above, for photons on the twelfth path to produce a thirteenth path, blocking photons as recited consistent with step (c);
(m) combining any photons on the eleventh path with unblocked photons on the thirteenth path in a seventh beam splitter that passes photons into a fourteenth path and a fifteenth path;
(n) detecting any photons on the fourteenth path;
and,
(o) detecting any photons on the fifteenth path.

12 more elements

An apparatus for direct counterfactual quantum communication comprising:

(a) a photon source emitting photons in a first state;
(b) means for transmitting a photon in a first state to a first beam splitter;
(c) a first beam splitter configured to randomly cause the photon to take either a first path or a second path;
(d) a second beam splitter configured to randomly split a photon on the second path into a third path and a fourth path;
(e) means for selectively blocking a photon on the fourth path;
(f) a third beam splitter configured to combine photons on the third path with unblocked photons on the fourth path and pass photons into a fifth path and a sixth path such that, if constructive interference occurs, the probability of finding a photon on the sixth path is greater that if constructive interference does not occur;
(g) means for blocking photons on the sixth path if photons were blocked on the fourth path;
(h) a fourth beam splitter configured to combine photons on the fifth path with unblocked photons on the sixth path and pass photons into a seventh path and an eighth path such that, if constructive interference occurs, the probability of finding a photon in the eighth path is greater than finding a photon in the sixth path and if no constructive interference occurs the probability of finding a photon in the eighth path is approximately equal to the probability of finding a photon in the sixth path;
(i) means for blocking photons on the eighth path if photons were blocked on the fourth path;
(j) a fifth beam splitter configured to combine photons on the seventh path with unblocked photons on the eighth path and pass into a ninth path and a tenth path such that, if constructive interference occurs, the probability of finding a photon in the tenth path is equal to the probability finding a photon in the second path;
(k) means for detecting any photons on the tenth path;
(l) a sixth beam splitter configured to combine photons on the ninth path with photons on the first path and pass photons into an eleventh path and a twelfth path such that, if constructive interference occurs, the probability of finding a photon in the twelfth path is greater than the probability of finding a photon in the twelfth path if constructive interference does not occur;
(m) at least one additional iteration of elements (b) through (l), above, configured to combining any photons on the eleventh path with unblocked photons on the thirteenth path in a seventh beam splitter that passes photons into a fourteenth path and a fifteenth path;
(n) means for detecting any photons on the fourteenth path;
and,
(o) means for detecting any photons on the fifteenth path.

13 more elements

Dependencies are inferred from the claim text.