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• id Quantique (Switserland)
• MagiQ Technologies (USA)
• SmartQuantu

We already have commercial quantum cryptography systems http://www.idquantique.com/ http://www.magiqtech.com/. And yes, those implementations are probably breakable in theory (they have no security proof covering the particuar implementations and they may be vulnerable to certain side channel attacks). However, by identifying side channels and bounding the information leaked through them and carefully monitoring that the devices are behaving as expected it should be possible to implement quantum cryptography which is unbreakable by any adversary bounded by the laws of quantum mechanics.

The Kish scheme on the other hand is secure against an adversary bounded by the circuit model. Now, the circuit model is not a fundamental theory of nature -- quantum mechancs is.

If by "Quantum encryption" you mean "Quantum key distribution" then you are incorrect. It is available commercially now.

One question, what magical technology have we got that can transmit and receive these qubits?
(if possible please refrain from using the word laser or photodiode)

I read on their site a wonderful description (here if you are interested):

The interaction between ions and single photons is quite weak; therefore it has to be enhanced by placing the trapped ions inside an optical resonator (i.e. between two very good, suitably arranged mirrors). This leads to a strong coupling between the light field in the resonator and the ions. Shining appropriate laser pulses on the ion in question, its state can then be mapped to the state of the resonator field (see, e.g. [6]. Similarly the state of the resonator field can be mapped on the state of an ion. To complete the interface, the resonator field must be coupled to a traveling light field, e.g. in an optical fiber. For the output, one can just wait for the photons in the resonator to leak out into the transmission line. For the input, more care is needed to circumvent the reflection of most incoming photons at the mirrors, but carefully designed laser pulses may "open up" the resonator to incoming photons. These proposals are quite close to what can currently be done in the lab, and their realization should be achieved in the coming years.

In other words, shining a laser through a filter at both ends.
If the length of the cable increases or is flexed sufficiently the frequency sync won't match and oh look your machine will tell you it has been modified.

It is literally a smoke and mirrors problem.

I was about to post the same thing after reading this from the "MagiQ" website, linked from the article. The paragraph entitled "Quantum Cryptography" is very informative, assuming it is accurate.

IRC, is that recorded?
Yes and no. It can be, so assume it is. It is, however, normally recorded by a user or bot on the channel for archival purposes. See http://ds9a.nl/klogbot/ for an example.

I don't know why computer communication isn't given the same legal protections as phone conversations. In most states, intercepting a phone call is illegal, and so is recording them without concent. How is communicating with a computer different than communicating with a phone?
Because in _most_ cases "computer communication" means the Internet and relies on "public" systems to relay messages. Telephone conversations, OTOH, are a "dedicated" connection between two people who have "leased" lines. You can do this with computers as well (even using quantum security, http://www.magiqtech.com/ ,) but it is not the Internet. In the case of IRC, you are posting to a semi-public forum, not to one person over a private connection.

How can I encrypt my emails so the person recieving can read them, but everyone else can't?
GPG, PGP, etc.

The technology is moving faster than you might think. Quantum Cryptography is already a commercial product sold by a couple of different companies such as MagiQ. The really cool part is that QC is good enough now days to be run over existing commercial fiber-optics. So the infrastructure is already in place. Just buy a couple of end-points and rent some fiber from the Telco and your on your way.

No, they are not wasting their time...because they aren't trying to send information faster than c. The computational benefits of entanglement have nothing to do with sending information at high speeds. It's mostly about doing many different calculations (factoring, searches, etc) simultaneously. The only place where QM plays into something like networking is where it is used to create bullet proof connections between two boxes (for something like a bank transfer). Check out: http://www.magiqtech.com/ In conclusion, NOTHING goes faster than the speed of light. Period.

I think you are missing the point. A single photon of light is sent down an optical channel made out of artificially produced diamond particles. The sender measures the photon using one of two methods A or B. Which method is used is randomly determined. The measurement results in one of two values (i.e. left or right, up or down.) The sender records the method of measurement and the determined value. The two measured states represent 1s and 0s in binary. The photon travels down the channel to the receiver. The receiver measures the photon using either A or B. Also determined at random. When the stream is complete the receiver tells the sender which measurement method was used for each photon. The sender then tells the receiver which photons were measured with the same methods. The binary data from any photons that were not measured with the same method is deleted from the message. This results in a series of 1s and 0s. Please note - even at this point the message can not be compromised - because THERE IS NO MESSAGE!

The next step in the process is validating the security of the transmission. This is done by comparing the binary results for matching photons. There are several ways to do this. One way is to use a process that splits the binary list into blocks using randomly chosen members of the list so that the list can be compared a block at a time. By comparing blocks at different parts of the list any interception of the data can be detected. How? If two photons were measured with the same method and the measurements don't match it means the data was corrupted. This could result from noise of various kinds, including interception. Too much noise is a strong indication of eavesdropping. Remember - the eavesdropper can only choose one of the two measurement methods and once the photon is measured the other measurement method is rendered invalid. That's why they call it "quantum". So for any photon measured by the eavesdropper there is a chance the receiver will get the wrong binary result even with the measurement method that matches the sender. Enough wrong matches and the eavesdropper is exposed. At this point there is still NO MESSAGE!

If they determine that no interception has occurred they use a normal bit parity check to eliminate errors. After each segment of the check they discard a bit from a prearranged location in the block (first, last, etc.) to reinforce security. By making the block sizes bigger as errors are discarded they eventually derive usable bit lists. These bit lists are then modified by prearranged formula and the resultant string becomes the key. And it is at that point that there is finally a message.

Currently, commercial quantum cryptography systems are available, but they are are expensive. Some major players in the development of quantum cryptography systems include IBM, NEC, DARPA, Toshiba, Fujitsu, MIT and Harvard. There are sure to be breakthroughs and roll-outs in the near future. Interestingly, one problem affecting the implementation of this new technology is the transmission of data over distances. Optical amplifiers evidently 'observe' the photons, thus rendering them useless. I guess that's just more proof that there really is a 'ghost in the machine'.

billy - who has nothing he needs to encode

There are actually commercial products (MagiQ) that do quantum encrypted links over fiber. If this product is properly made, I could well see it obsoleting any classical crypto tunnels (like VPN etc). Hell, you just layer the classical crypto over the quantum secured link anyway. I have recently been talking with professors at a major North American university who will in fact be dissecting this equipment; but yeah, classical crypto simply can't compete with equipment like this. You put up the quantum crypto link on fiber, then any classical crypto underneath.

Here is a whitepaper from MagiQ on their technology.

That and a lot more signals can simultaneously use the same fiber, forgot the number, but I think its around a thousand per optic fiber and less than a hundred for copper...

That is interesting that we can use photons of different energy (i.e. light of different colour) causing hardly as much interference as with superposition of electromagnetic signals of different frequency even in the best hyperconductive wire. I won't even mention completely new applications which are only starting to get developed.

There is no such thing as a true "random number generator". The only exception is in quantum mechanics, which is impossible to use at the moment

It says here that the maximum 2 of these can span is 120km. They also say a bit farther down that if you wanted it to go farther, you could daisy chain them together.

According the the Sep. 6th issue of The Economist there is a company in Massachusetts called MagiQin the final stages of testing a system which it plans to release commercially in the next few months.

"The scheme devised by MagiQ, called Navajo, does not use quantum effects to transmit the secret data. Instead, it is the keys used to encrypt the data that rely on quantum theory. If these keys are changed frequently (up to 1000 times a second in Navajo's case), the risk that an eavesdropper without the key would be able to decrypt the data can be proved mathematically to be zero.

mathematically unbreakable.

but we've heard that before.

"Just add another wheel to the Enigma machine Hermann. Those dim-witted English shopkeepers vill never figure it out... "

so do these guys

One comment: even if you need to cool your detector to cryogenic temperatures, you don't have to have your customer pour liquid nitrogen (or did they say liquid helium?) into the commercial device. This is what compact no-maintenance closed-cycle coolers are for.

Plug #1: idQuantique
Plug #2: Magiq Technologies
Plug #3: Los Alamos lab (yes there used to be a site there)
Plug #4: Our own research (not commercially-oriented yet)

The laser-based system hopes to eventually bounce the signals off mirrors on satelites, sending keys anywhere in the world. (For a price... good for diplomats and military I suppose.)

The fiber systems are still in need of a repeater-like device before they can get more significant distances.

Hello - there's a company in NYC and the Boston area actually designing quantum encryption technology for eventual products. They have a team of heavy-hitters in the quantum information world. They're called MagiQ Technologies, Inc.

I know their CEO, and it sounds like they're doing very promising work. They've been pretty quiet about their stuff, but think that it's an example of the real-world applications of this type of technology.

Gregg Favalora - CTO, Actuality Systems, Inc. - The 3-D Display Guys