Quantum Bayesian Networks

August 31, 2011

Conjecturing and Manufacturing a New Kind of Quantum Particle

Filed under: Uncategorized — rrtucci @ 2:09 am

Bad science articles often make the very misleading claim that nobody really understands quantum mechanics. Maybe the foundations of quantum mechanics are not understood well (i.e., whether there is a more basic theory underlying quantum mechanics). However, quantum mechanics itself is understood so well that physicists have enough mathematical machinery, understanding, and hubris to conjecture with confidence a new kind of quantum particle, and to tailor design a new solid state material that will generate it! The new particle, called the Majorana fermion (MF), has never been seen before by man.

Elbowing the competition: Unlike the less useful new particles observed with the multi-billion dollar Large Hadron Collider (LHC), quantum computerists expect their solid state MFs to have many practical applications and to be cheap to generate. They plan to use solid state MFs to make quantum computers. If we can build them, QCs will perform certain calculations faster (i.e., with a more favorable time complexity) than current non-quantum computers, plus QCs may elucidate the very foundations of quantum mechanics.

The story of MFs is a real-life detective story filled with challenging puzzles and “what will happen next?” suspense.

(Ettore means Hector in Italian. In Homer’s Iliad, Hector was the bravest warrior on the Trojan side. He was killed by Achilles.) Ettore Majorana was born in 1906 and went missing in 1938. In those 32 years, he wrote just 9 papers, but they were good enough to make him famous. Enrico Fermi (a Nobel prize winner who worked with some of the greatest physicists of his time, like von Neumann, Feynman, etc.) was one of Majorana’s mentors and considered Majorana’s talent for physics equal to that of a Newton or a Galileo. Majorana was probably the first to hypothesize neutral protons (what we now call neutrons) before they were discovered in the lab. He also hypothesized massive neutrinos, something that took more than half a century to be taken seriously. More importantly for quantum computing, in 1932, he wrote down an equation, now called “the” Majorana equation, very similar to “the” Dirac equation.

The Dirac equation predicts two different types (electrons and positrons) of fermion particles that are anti-particles of each other and can annihilate each other. On the other hand, the Majorana equation predicts only one type of fermion particle (Majorana fermion) which is its own anti-particle and can annihilate a copy of itself. (The Dirac equation has complex-value field solutions whereas the Majorana equation has real-valued field solutions. According to Majorana, this is analogous to a Dirac particle requiring 4 wheels to move through space-time, like a car, versus a Majorana particle requiring only 2 wheels, like a bicycle or motorcycle).

Majorana disappeared under mysterious circumstances during a fairly short boat trip from Palermo to Naples. Many claim that he didn’t commit suicide or drowned accidentally, but that instead he faked his own death. Some say that he fled to a monastery or to Argentina and lived there anonymously for the rest of his life.

Another major Majorana mystery is where are the MFs? Scientists have neither found nor manufactured any MFs yet, almost 80 years after Majorana hypothesized their existence.

None of the “elementary” particles that have been observed so far by High Energy physicists are MFs. MFs occur in supersymmetric theories, but there is no evidence for such theories yet. It’s possible that neutrinos are MFs, but they could also be Dirac fermions. We still don’t know which one for sure.

MFs are expected to occur as “quasi-particles” in certain solid state systems, but even there, they are just a hypothesis. We still haven’t proven their existence experimentally or measured or harnessed their properties.

Anyons are particles that obey “any” statistics; i.e., statistics that are different from those obeyed by particles with half-integral spin (fermions) or integral spin (bosons). Scientists believe that nonabelian anyons could be used to make embarrassingly long-lived qubits. The reason for this expectation is that nonabelian anyons are protected by topology, and have no easy means of decohering by interacting with the environment.

Free MFs moving in 3D space obey spin 1/2 statistics. However, if MFs are confined to a 2 dimensional surface, they will instead obey nonabelian anyon statistics. To make a good qubit, it is also desirable that an MF remain close to a point (i.e., be localized) as occurs if it’s in a bound state.

Many labs are currently racing with each other to be the first to produce 2D bound MFs that are usable as qubits. They are looking for such MFs, for example, on the surface of a 3D topological insulator that is in close proximity to a superconductor. The MFs occur where the superconductor vortices intersect the surface of the topological insulator.

If you want to read a little more about the exciting race to build solid state MFs, check out the following introductory articles:

August 20, 2011

Hewlett Packard’s Brilliant, Bold, $11 Billion, Bayesian Bet

Filed under: Uncategorized — rrtucci @ 6:40 pm

An historic event for Bayesians and for the software industry. HP is going to pay $11 billion to acquire Autonomy, a software company that specializes in Bayesian search engines. ($11 billion is about one-sixth of HP’s current market value.) Not only that, but HP also intends to get out of the PC, smart phone and touch pad businesses!

The PC hardware business ain’t what it used to be. And competing against Apple right now is like trying to walk through a cement wall instead of going around it. IMHO, the future of American high-tech industry belongs to companies like HP that are willing to make smart, bold, original decisions like this one. Bravo HP! Bravo! The stock market’s response to this news has been Palin dumb. HP’s stock fell by 20% the day after the acquisition was announced. Cretins@#% My advice: Buy! Buy! Buy!

Autonomy is UK’s largest (by market capitalization) software company, the flag-ship of the royal fleet. HMS Autonomy is commanded by the legendary Sir Francis Drake, Admiral Horatio Nelson, HMS Pinafore Captain Corcoran, Dr. Mike Lynch. I spoke previously about Autonomy in the following blog post: Bayesian Networks in the UK

Hewlett-Packard is a worthy Queen for Admiral Lynch to serve. Her history (both her inspiring triumphs and her abysmal blunders) are EPIC. Queen HP is the original cornerstone company of the Silicon Valley miracle. A lot of scientists and engineers grew up using HP equipment. She built my first oscilloscope. She is more profitable than IBM (revenues(2010): HP-$126B/IBM-$100B). In 2010, she had 325K employees versus IBM’s 427K. She once rejected a proposal by one of her engineers, a guy named Christopher Columbus Steve Wozniak, to buy the design for a home computer that he had invented.

The HP/Autonomy royal fleet will engage in battle with and try to sink a formidable, terrifying foe, a Spanish Armada built by very powerful and wealthy nations such as Google, IBM (with its intimidating Bayesian man-of-war, the Watson computer), Microsoft, Oracle and SAP. At stake is no less than supremacy over the Bayesian sea lanes and trade routes to the New World.

Someday in my lifetime, I predict HMS Autonomy will equip its cannon decks with quantum computers, for they are, according to computational complexity theory, pound for pound, the most efficient cannons (for doing certain tasks, e.g., Markov Chain Monte Carlo) that God will allow man to build.

Reports of various media outlets about HP/Autonomy deal

August 17, 2011

Why be a Physics Castrato When You Could be a Tenor or a Soprano?

Filed under: Uncategorized — rrtucci @ 8:47 pm

You could have been a contender.

If you had chosen to sing in the opera of quantum information theory, you could have sung as beautifully as Luciano Pavarotti or Maria Callas (La Divina). But instead you chose String Theory.

At one point, the public thought you were one of the greatest tenors or sopranos in the history of mankind. You totally agreed. You still think it’s true. But with ZERO evidence for supersymmetry in the LHC data, the fickle, ungrateful public is growing weary of your voice and comparing your futile, impotent yelps and whines to those of a castrato.

Alas, your elegant universe is no more, at least in America. The Fermilab Tevatron is not long for this world. And what is to become of Fermilab’s Wilson building, that imposing, inspiring grand opera house for particle physics? Its Lambda profile /\ could be turned overnight into a W profile by the simple expedient of building a tower on each side of the Lambda. Would make a nice W-almart. Much needed in Batavia, Illinois, in these hard times.

So what if we find “God’s particle”? Mere spectroscopy. Verifying “spectra” predicted by a theory that is old hat by now. Instead, you could be building God’s computer, the Vatican’s computer, i.e., a quantum computer. Imagine owning your own QC and programming it to do kooky things. The audience would love it. Bravo!! Bravo!! Bellissimo!!

“You don’t understand! I could’ve had class. I could’ve been a contender. I could’ve been somebody, instead of a bum, which is what I am, Charley, let’s face it.”
Marlon Brando as Terry Malloy in the film “On the Waterfront” (1954)

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