As I See It: Sub-Atomic Dreams
October 22, 2012 Victor Rozek
Theoretical physicist Brian Greene once observed: “No matter how hard you try to teach your cat general relativity, you’re going to fail.” God knows I’ve tried, but my cat is just not interested in relativity. That’s so yesterday. She wants to learn quantum mechanics. But the thing about quantum mechanics is that only a handful of people on the planet can truly claim to understand it. And that’s probably an exaggeration. Even Einstein called it “spooky.”
Not only is the math beyond the capabilities of the average smartphone, but concepts like “superposition,” “entanglement,” and “decoherence” have about as much in common with our daily experience as Clarence Thomas has with asking questions during Supreme Court hearings.
At its most basic, quantum mechanics is a theory that purports to explain the fundamental workings of nature. But it is notoriously counterintuitive. It predicts, for example, that a particle can be in two places at the same time, sort of like Santa. And, like Santa, quantum mechanics requires a healthy dose of suspended belief.
Contrary to common opinion, superposition does not refer to Hulk Hogan’s pose in his recent sex video. Nor, as scientific concepts go, is it totally beyond the grasp of the average confused human being. It can be metaphorically understood by anyone willing to admit they frequently hold two contradictory thoughts and believe them both to be true. Like “money can’t buy happiness” and, “I could be happy if I just had more money.”
Superposition describes the ability of a quantum system to be in multiple states at the same time. Particles, for example, can be “here” and “there,” or “up” and “down,” all at the same time, kind of like God only a lot smaller. Just like supermarket tabloids, quantum theory traffics in the improbable. In the quantum world, not only can particles exist in all possible states simultaneously, but they can only maintain a multiple state of being as long as no one is checking up on them. Observing the object causes it to be limited to a single possibility. The observer changes the observed; not unlike a guard monitoring Bernie Madoff in a prison cell when he knows he’s being watched.
It’s a good thing that teenagers haven’t caught on to using quantum mechanics as a defense strategy. “Yes, you caught me, but I’m only smoking pot because you observed me doing it, thus limiting me to one possibility. Otherwise, I’d also be in a non-smoking state.” (Oops, I think I just let the quantum cat out of the Ziplock baggie.)
Entanglement refers to the powerful and mysterious connection that exists between quantum particles, sort of like the connection between money and politics. In fact, two or more quantum particles can remain inextricably linked and “dance” in perfect unison even if separated by pretty substantial distances like, say, the universe. No one knows how these particles communicate, but experimental results have demonstrated that, however the transmission occurs, it travels at least thousands of times faster than the speed of light which, of course, the brilliant guy with the fuzzy hairdo proved wasn’t possible.
In any event, all of this happens at the sub-atomic level, so who cares anyway? IBM for one, as well as research labs around the world seeking ways to store, transmit, and process information encoded in systems that use these fanciful quantum properties. The prospect of quantum computing has been tormenting researchers since Richard Feynman suggested the possibility back in 1982. The fact that 30 years later the field is still in its infancy speaks to the daunting challenges of the sub-atomic world. And that’s where decoherence rears its unruly head.
As we know, the data in conventional computers is encoded in strings of bits. Ones or zeros, on or off. Quantum computing uses qubits, which could be on or off or on and off, thus providing extreme speed and flexibility. Qubits can be made of photons, or atoms, or electrons, or molecules, or maybe something else altogether. Scientists are testing a variety of options looking for stability. The dilemma is, they have to be able to manipulate qubits but, like my cat, qubits can’t be disturbed. It’s that pesky observation problem, which reduces the computing advantages of superposition to a single state. Disturb my cat and she will scratch you; disturb a qubit, and it “decoheres” or falls out of its quantum state. And decoherence, according to the Institute of Quantum Computing (IQC), is quantum computing’s “Achilles Heel.”
IBM, however, appears to be on its way to solving that problem. Researchers created a high-coherence 3D qubit (do you need funny glasses to see it?) that retains its state for up to 0.1 milliseconds. Not nearly as long as a wait in the emergency room, but in the quantum world, long enough. But why even bother? It is estimated by IBM brainiacs paid to estimate such things that 250 qubits would be able to store “more bits of information than there are atoms in the universe.” As big numbers go, that’s impressive, even though it’s totally made up. But beyond storage capacity, a quantum computer could perform logic on all of that data, in parallel, instantaneously. And for all we know it could probably juggle kitchen knives while singing Babalu.
The ability to process a vast number of calculations simultaneously is certainly advantageous for mathematical computations previously thought to be intractable, but it is unlikely to have a near-term impact on consumer technology. Why use a flame thrower when all you need is a match. A full-blown quantum computer is still years if not decades away. To date, the largest number of qubits successfully used in an experiment stands at 12. But there are aspects of quantum computing that are inching their way to the marketplace.
Data security will likely be the first beneficiary. Currently, encryption keys rely on math problems that are too hard to solve for conventional computers. But quantum computers would make short work of deciphering conventional keys. The advantage of quantum keys is that they are unbreakable. Snooping will become impossible and thousands of government employees will be looking for other work.
IQC has developed a Quantum Key Distribution prototype using photons (particles of light) generated by a laser. A pair of photons are transmitted, one each to two devices placed at some distance from one another. Because of the entanglement properties of quantum mechanics, each photon will be identical. According to IQC, “photons have a unique measurable property called polarization,” not unlike sunglasses. But the polarization of each individual photon is random and cannot be predicted. When the polarization on the two photons is measured, they should be identical unless, of course, an unscrupulous third party was attempting to spy on the transmission. Then the system will decohere and the transmissions won’t match, alerting the sender. The more photons transmitted, the more complex the key.
But perhaps the Holy Grail of quantum computing lies in the ability to study “the interactions between atoms and molecules” on a scale previously unimaginable. Deeper understanding of the molecular world will facilitate the creation of a wide array of designer drugs and engineered materials whose properties could be fully tested before construction. Still, all of this is projection based on what we know today. “The true potential of quantum computers likely hasn’t even been imagined yet,” say the researchers at IQC. “The inventors of the laser surely didn’t envision supermarket checkout scanners, CD players, and eye surgery.” Or, for that matter, laser pointer cat toys.
Speaking of cats, mine is yowling, demanding to be let in. I open the door and there she stands straddling the threshold. She has assumed a superposition: neither in nor out, yet both in and out. She is demonstrating mastery of quantum mechanics, and she stands there making sure I have enough time to admire her. Sure enough, as soon as I begin to pay attention, she decoheres and enters the house. Quick learner. What’s next, I wonder. String theory?