Comics are supposed to be fun, light reading. Something I read on MSNBC’s Comics & Games website has been on my mind for a few months. The column titled "News of the Weird" by Chuck Shepherd (March 30, 2008) had one paragraph that caught my attention.
"A team of researchers from the University of Calgary and the Tokyo Institute of Technology proudly announced in February that they had successfully stored "nothing" inside a puff of gas and then had managed to retrieve that same "nothing." That "nothing," is called a "squeezed vacuum," and the physicists tell us that a light wave can be manipulated so that its phases are of uncertain amplitude, then the light itself removed so that only the "uncertainty" property of the wave remains. ScienceNOW Daily News, 2-29-08"
I can hear the conversation now:
Mom, "What did you do in school today?"
Graduate Student (still on mom’s tab) "Nothing."
I know that didn’t cut it when I was in school, and my reply was closer to the truth.
It turns out that the article in ScienceNOW is titled "Physicists Successfully Store and Retrieve Nothing." This is an abstract of a news release from the University of Calgary titled "Physics breakthrough much ado about ‘nothing.’" If Adrian Cho, author of the ScienceNOW abstract or Grady Semmens author of the public release from the University of Calgery had used the title of the paper they were describing, "Quantum memory for squeezed light,"(1) noone would have read it. The fact is, that in the entire Quantum Memory paper, the word "nothing" is never used to describe what the physicists input or retrieved in their experiment.(2)
Physicists at University of Calgary and the Tokyo Institute of Technology have brought a "light" pulse to a stop and retrieved the pulses from an rubidium/neon vapor. The retrieved "light" is in the form of a squeezed vacuum pulse that has reproduced the characteristics of the input pulse. When I took Physics in college, forty years ago, the speed of light was sacred. The professor would not even consider deviations in this constant. Today we read about physicists that slow, stop and bottle light. These are indeed exciting times.
So what is this "nothing?" A misnomer, the nothing is called a squeezed vacuum but there is no vacuum involved.(3) Normal light can be represented in the form of the characteristic sine wave on an oscilloscope, a smooth wave of electromagnetic energy with equally spaced peaks and troughs. In quantum mechanics the view of this same light reveals a degree of uncertainty. The sine wave is no longer a precise line but a fuzzy representation of the electromagnetic wave. Physicists can now manipulate the quantum light wave to concentrate the uncertainty creating phase-squeezed light. The phase-squeezed light has concentrations of uncertainty in the peaks and troughs and less uncertainty in the mid point. If the light signal is turned to zero the uncertainty remains in pulses but the sine wave disappears. Science writers have called these pulses of uncertainty "nothing" and the physicists call them a squeezed vacuum. These are pulses of quantum noise. (4)
In the experiment conducted at the University of Calgary, physicists directed two lasers beams into a magnetically shielded cell containing a rubidium vapor with a neon gas buffer.(5) The stronger laser is the control laser, the squeezed vacuum pulse laser is the signal pulse laser. The control laser and signal pulse laser are linearly polarized which allows for separation as they exit the cell.
The control laser creates an electromagnetic induced transparency (EIT) (6) in the rubidium vapor. The control laser is tuned near resonance to interact with the quantum state of the rubidium vapor causing the EIT transition. The EIT caused by the control laser excites the rubidium atoms into a collective orientation spin pattern (the individual atoms align their spins creating what might be considered the equivalent of a gas magnet). (7)
The signal pulse laser is tuned to interact with the absorption spectrum of the rubidium. To trap the signal pulse, researchers turn off the control beam, and the signal pulse microseconds later, which causes the signal pulse to imprint itself on the rubidium atoms slowing the signal pulse’s group velocity to zero and storing its information in the form of an atomic "spin wave"(8) on the collective excitation of the rubidium atoms. (9)
To release the stored pulse again they turn on the control laser accomplishing the non destructive and reversible conversion of the information carried in the squeezed vacuum pulse. These experiments have shown that a quantum state’s nonclassical (10) character is preserved after storage and retrieval (11) This technique was proposed theoretically by Lukin, Yelin and Fleischhauer, Phys. Rev. Lett. 1 May 2000 and Fleischhauer and Lukin, Phys. Rev. Lett. 29 May 2000 and accomplished by both teams recently. (12)
The point of this research is secure - quantum cryptography, quantum communication and quantum computing. What has developed is a quantum "arms race" among national groups that should be cooperating. On one side the English speaking world, US, UK, Canada, Australia and New Zealand represented by ECHELON. On the other side the EU represented by SECOQC.
ECHELON is a name used by the global media to describe a intelligence collection and analysis network operated on behalf of Australia, Canada, New Zealand, the United Kingdom and the United States. You can visit their web site (but you can’t get in) at:
ECHELON was investigated by a committee of the European Parliament during 2000 and 2001. The EU committee produced a document from this investigation that you can download from:
This document describes the political and economic espionage potential of ECHELON based on the fact that this organization is capable of interception and content inspection of telephone communications, fax, e-mail and virtually all other data traffic.
The heart of ECHELON according to the EU committee are the various intelligence gathering organizations of the participating countries:
Defense Signals Directorate
Communications Security Establishment
Government Communications Security Bureau
Government Communications Headquarters
National Security Agency
Initially ECHELON was created to monitor the Soviet Union and its Warsaw Pact allies during the Cold War. It targeted military and diplomatic communications of that era. Even today this network has a valid mission, to search for terrorist plots, disrupt drug-dealers’ operations and monitor political and diplomatic communications from nations hostile to the group.
The EU committee report claims that ECHELON is also being used for large-scale commercial theft, inter-nation economic espionage and invasion of privacy. The EU feels targeted and has take specific actions including the development of quantum technology to protect itself. In a SECOQC news release (13) Dr. Christian Monyk states, "We will provide a tool, based on quantum technologies, which will enable economical enterprises to guard their assets against industrial espionage. In the past, significant financial losses due to industrial espionage had to be attributed to activities of the ECHELON communication surveillance and interception network. Our aim is to make a significant contribution to the independence and competitiveness of the European economy." Dr Monyk is head of the business unit at Quantum Technologies.
There is a basic investigative principal - follow the money. Both sides are investing heavily in quantum technology. In the U.S. a quantum cryptographic research project as a joint collaboration between Northwestern University and BBN Technologies of Cambridge, Mass., is supported by a five-year, $5.4 million grant from the Defense Advanced Research Projects Agency.(14) In the EU funding of 11.4 million Euros has gone to SECOQC, a consortium of 41 participants from twelve countries consisting of twenty-five universities, five national research centers, and eight private enterprises. (15)
Both sides are claiming a first in quantum communication. In the EU, Quantum Key Distribution (QKD) (16) made its real-world debut in Geneva, Switzerland for use in one of the electronic voting systems used in the Swiss general election last year.(17) The test of the technology demonstrated that QKD worked for point-to-point secure communication. In the U.S. BBN has built and demonstrated what they are calling "the world’s first quantum network," using a quantum data encryption protocol called AlphaEta, delivering end-to-end key distribution via high-speed QKD since 2004.(18) The combined QKD/AlphaEta system has been demonstrated in a nine kilometer link between BBN headquarters and Harvard University in Cambridge, Mass. In one test, the AlphaEta encrypted signal was looped back multiple times to create an effective 36 kilometer link where more than 300 consecutive key exchanges were demonstrated, this is not your traditional network.
SECOQC’s researchers believe thay have solved the network issue. The researchers are currently putting the final touches to a demonstration of the technology to be held this October 2008 in Vienna, Austria. Dr. Monyk, of the SECOQC project and head of the quantum-technologies unit at the Austrian Research Centres said, "Network quantum encryption and QKD mean that many parties can communicate securely, not just two. Finally, it also means quantum encryption could be deployed on a very large scale, for the insurance and banking sectors" (19) I can not imagine the NSA walking away from this challenge, some day we will read of the obvious flaws in quantum encryption and secure QKD.
(1) Appel, Jurgen, Figueroa, Eden, et al., Quantum Memory for Squeezed Light, February 1, 2008, arXiv:0709.2258v4
(2) There is no defined term for changing a title to get the readers attention. In a post from Professor Mary Beth Debs of the University of Cincinnati she states, "the move would be called "sensationalizing" or "populatizing." We could make an argument that it’s a "hanging head" - essentially, it leaves the reader hanging without key info. That is a term usually used with a more specialized title, but could work here." Using the term "nothing" in this way is and artificial enhancement.
(3) In classical mechanics the idea of a vacuum was simple. The vacuum was what remained if you emptied a container of all its particles and lowered the temperature down to absolute zero. Quantum mechanics has completely changed our notion of a vacuum. (Wikipedia) Applying the term to light can be puzzling.
(4) Quantum noise is uncertainty of some physical quantity due to its quantum origin.... quantum noise refers to the fluctuations of a signal in extremely accurate optical systems with stabilized lasers and efficient detectors. (Wikipedia)
(5) ibid 1. Their setup was both state-of-the-art, and seat-of-the-pants technology. They used "pulsed, time-domain homodyne tomography" and the "continuous variable domain of quantum optics." To "chop" the laser beams into microsecond pulses, they "employ(ed) an ultra-fast mechanical chopper custom-made from a standard 3-inch computer hard disk...with a 50 um slit cut through."
(6) Electromagnetically induced transparency (EIT) is an effect in which a medium that is normally opaque at a particular wavelength is caused to become temporarily transparent. EIT is a coherent optical non-linerity which renders a medium transparent over a narrow spectral range within an absorption line. (Wikopedia)
(7) Physics News Update, Number 521 #1, January 18, 2001 by Phil Schewe, James Riordon, and Ben Stein.
(8) ibid The signal pulse "interacts with the atoms changing the atoms’ spin state coherently and creating a joint atom-photon system known as a polariton." The polariton, the light-atom interaction, causes the massless photons to act as if they have an effective mass. The energy of the squeezed pulse is stored in the atomic spin wave, waiting to be released as a light pulse that is in principle identical to the incident pulse. "After a relatively long delay the control beam can be turned back on, reverting the polariton to being a light wave by coaxing the atoms to emit the exact signal light pulse that entered the medium."(9) ibid
(10) Nonclassical light is any state of light that cannot be described using classical electromagnetism, its characteristics are described by the quantised electromagnetic field and quantum mechanics. Nonclassical light has nonclassical noise properties called quantum noise which can be understood on the basis of quantum optics. A common form of nonclassical light is Squeezed light that exhibits reduced noise in one quadrature component, The most familiar kinds of squeezed light have either reduced amplitude noise or reduced phase noise. The quantum mechanical version of a classical light wave is the coherent state of the quantum electromagnetic field (Wikopedia)
(11) ibid. 1
(12) ibid 6
(14) Northwestern University (2006, August 29). First Quantum Cryptographic Data Network Demonstrated. Science Daily, Retrieved May 14, 2008, from http://www.sciencedaily.com/releases/2006/08/060828211555.htm
The Defense Advanced Research Projects Agency (DARPA) in the 1960's developed the communication protocol that is the backbone of today’s internet.
(15) ibid 12
(16) Quantum Key Distribution (QKD) exploits the unique properties of quantum mechanics to securely distribute electronic keys between two parties, unlike traditional key distribution which can be intercepted. The "key" is heart of encrypted communication, it encrypts the message to be sent and decodes the message that is received
(17) ICT Results (2008, April 29). Beating The Codebreakers With Quantum Cryptography. Science Daily. Retrieved April 30, 2008, from http://www.sciencedaily.com/releases/2008/04/080428123555.htm
(18) ibid 13
(19) ibid 16