Sunday, July 26, 2009

Quantum Tic Tac Toe

Quantum mechanics is notoriously difficult to understand because our species evolved in a classical world. Even physicists who are familiar with the quantum math still experience this world classically. Niels Bohr believed that this would always be the case. "No matter how far the explanation of quantum phenomena transcends classical notions, " Bohr said, "the results of all experiments must be expressed in classical terms." In order to think like Nature thinks we must learn to think quantum-mechanically. But where can we go to exercise our minds with quantum experiences?

Recently Alan Goff, a researcher at Novatia Labs, invented a quantum version of tic tac toe which he presented at the unlikely venue of a meeting of the American Institute of Aeronautics and Astronautics. Perhaps Goff hoped that insights gained from playing quantum tic tac toe might lead to breakthroughs in space propulsion physics. Later he published an account of his new quantum game in American Journal of Physics which is primarily directed towards physics teachers and welcomes clear reviews and novel presentations of complex ideas. AJP is Nick's favorite physics journal.

Goff has a blog called Alan Goff's Entanglements where he discusses quantum TTT and other topics.

If you want to learn to play quantum TTT, the rules are published here, along with a Java applet that maps all the moves in real time.

In a nutshell, on each turn, a player marks two squares at once with two "spooky marks". One square can be occupied by any number of spooky marks, in which case the marks are said to be "entangled". The play proceeds, each player marking the board with two spooky marks until player A makes a move which creates a "cyclic entanglement". Then player B chooses how that entanglement will "collapse" into "real marks" that can only occupy one square at a time as in classical TTT. After collapsing the cycle (and all "stems" entangled with that cycle) B makes the usual "spooky move" on any remaining two squares that do not contain collapsed marks. The game ends when one or both players gains a three-in-a-row of collapsed marks just as in classical TTT.

Quantum TTT is in many respects a nice metaphor for quantum reality. Before observation, a quantum particle can be in two places at once and be entangled with other particles in an instantaneous kind of connection impossible in the classical world. In the quantum world as in quantum TTT, a "collapse" which depends partly on the observer's choice and partly not turns spooky possibility into concrete actuality. In both the quantum world and in quantum TTT, an action in the future can seem to affect the past, but in either case no time-travel paradoxes arise.

I live in a redwood forest surrounded by trees. Inside each green leaf or needle are trillions of chloroplasts containing two kinds of chlorophyll--antenna chlorophyll which is specialized for absorbing light energy and reaction chlorophyll which is specialized for using energy to drive the chemical reactions that build the tree. Mediating between the antenna CHPHL and the reaction CHPHL are an array of transfer molecules. Up until a few years ago it was believed that a photon absorbed by an antenna CHPHL tranferred its energy to the reaction CHPHLs via a classical random walk among the intervening transfer molecules till its energy happened to reach a reaction site or was lost. Now researchers have discovered that something analogous to a quantum tic tac toe game is going on inside every green leaf on this planet. Instead of following one path at random the photonic excitation takes many spooky paths at once till one of these paths touches a reaction site which collapses it and makes it real.

In the words of one of these chlorophyll researchers: "This wavelike characteristic of the energy transfer within the photosynthetic complex can explain its extreme efficiency, in that it allows the complexes to sample vast areas of phase space to find the most efficient path."

When you look up into the trees, can't you imagine a torrent of solar photons each triggering a spooky quantum TTT move that is efficiently sampling "vast areas of phase space"? Her everyday quantum subtlety multiplied trillions upon trillions of time in every green plant is one more reason to praise the goddess chlorophyll from whom so many of our blessings flow.

Wednesday, July 22, 2009

The Day The Saucers Came


That day, the saucers landed.
Hundreds of them, golden,
Silent, coming down from the sky
like great snowflakes,
And the people of Earth stood and stared
as they descended,
Waiting, dry-mouthed to find
what waited inside for us
And none of us knowing
if we would be here tomorrow
But you didn't notice it because

That day, the day the saucers came,
by some coincidence,
Was the day that the graves gave up their dead
And the zombies pushed up through soft earth
or erupted, shambling and dull-eyed, unstoppable,
Came towards us, the living,
and we screamed and ran,
But you did not notice this because

On the saucer day,
which was the zombie day, it was
Ragnarok also, and the television screens showed us
A ship built of dead-man's nails, a serpent, a wolf,
All bigger than the mind could hold,
and the cameraman could
Not get far enough away,
and then the Gods came out
But you did not see them coming because

On the saucer-zombie-battling gods day
the floodgates broke
And each of us was engulfed by genies and sprites
Offering us wishes and wonders and eternities
And charm and cleverness and true brave hearts
and pots of gold
While giants feefofummed across the land,
and killer bees,
But you had no idea of any of this because

That day, the saucer day the zombie day
The Ragnarok and fairies day,
the day the great winds came
And snows, and the cities turned to crystal, the day
All plants died, plastics dissolved, the day
the Computers turned,
the screens telling us we would obey, the day
Angels, drunk and muddled, stumbled from the bars,
And all the bells of London were sounded, the day
Animals spoke to us in Assyrian, the Yeti day,
The fluttering capes
and arrival of the Time Machine day,
You didn't notice any of this because
you were sitting in your room, not doing anything
not even reading, not really, just
looking at your telephone,
wondering if I was going to call.

-----Neil Gaiman-----

Schrödinger's Carousel

Every club has its mascot and among my tribe of physicists no mascot is more fitting than Schrödinger's Cat.

Erwin Schrödinger was a sophisticated Austrian, a reluctant participant in the Quantum Revolution sweeping through Europe in the late 1920's. Schrödinger expressed his displeasure at the new quantum world he was helping to construct by focusing attention on its strangenesses. He was the first to notice that quantum entanglement--an odd kind of instant voodoo action--was an inescapable consequence of his own quantum equations when applied to two or more particles of matter.

And he was particularly troubled by the curious notion of quantum superposition. In theory at least, an atom could not only be in state A or in state B but could exist also in a superposition state 1/2 A and 1/2 B with some "quantum phase" between them. Today this superposition principle forms the basis for quantum computers which instead of manipulating binary bits 1 and 0, compute using "qubits", quantum superpositions of binary bits.

Schrödinger tried to demonstrate the absurdity of the New Physics by taking the notion of quantum superposition to extremes. If one could superpose any number of atoms, as the equations allowed, then why could not one superpose a cat in two different states, say, alive and dead? Schrödinger showed, in a famous thought experiment, exactly how this might be accomplished and left us with an image of not just an atom, but a macroscopic object (covered with fur) existing at the same time in two extremely different states of being.

The quantum rules describe the world as waves (of possibility) when not observed and particles (of actuality) when observed. So Schrödinger's Cat maintains her twofold existence only as long as she is wavelike, that is only until she is observed, whereupon she departs her superposition state (and in a manner complete mysterious to physicists) becomes definitively either dead or alive but not both.

Schrödinger's Cat has been the subject of much theoretical discussion and a kind of informal contest among experimentalists to see how big a system they can coax into a quantum superposition. Superpositions of "big" systems have come to be called "cat states" as in the case of a recent experiment at Oxford University in which researchers placed 13 nuclear spins in phased-linked superposition--Magnetic Field Sensors Using Large Cat States.

Thirteen spins may seem a long way from a 10-pound pussy cat, but the recent production of Bose-Einstein Condensates has now opened the way to manipulate not just a few spins but a few million rubidium atoms into a single state and then coax that state into a quantum superposition. The mass of a few million rubidium atoms is comparable to the mass of a virus so we are still a very long way from being able to quantum-superpose cats.

A Bose-Einstein Condensate (BEC) is a dilute gas of atoms confined by electromagnetic fields and cooled to a super-low temperature (a few nanodegrees above Absolute Zero) until the atoms collapse spontaneously into the same quantum state.

A new way to turn a BEC into a cat state was recently proposed by three theorists (Thanvanthri, Kapale and Dowling) at Louisiana State University. Instead of confining the BEC inside a simple potential well, TKD propose to use a "sombrero potential" for confinement. In a sombrero potential the particles are trapped in the brim of an electromagnetic Mexican hat to form a kind of "moat of quantum waviness" around the central peak of the hat.

Now that you have an unmoving "ring of bright water" made of quantum stuff, the next thing to do is to get that ring to rotate by shining light that contains angular momentum on the ring. When the BEC absorbs the spinning light, it too begins to spin, forming a Quantized Vortex State, a million atoms all rotating CW, say, around the central sombrero peak. You can also get the Vortex to rotate CCW by illuminating it with light spinning in the opposite direction.

Now comes the Schrödinger Cat part. Compared to getting matter to superpose, light is easy. So now you shine a superposition of CW and CCW light on the BEC and a million Rubidium atoms begin to swirl in two directions at once--an odd state of excitation one might call "Schrödinger's Carousel".

Make no mistake, Schrödinger's Carousel is not a simple classical situation where half of the atoms are rotating in one direction and half in the other, but a truly quantum state in which ALL OF THE ATOMS are rotating halfly CW and halfly CCW around the sombrero peak. Cool quantum cat, man.

But wait, there's more. Because this experiment is carried out on the Earth which is rotating once a day, one of the cat halves finds itself spinning slightly faster than the other which gives rise to a phase shift between CW and CCW vortex matter waves that can be easily measured. The Schrödinger Carousel then behaves as an ultrasensitive gyrocompass that can accurately pinpoint the direction of True North. Nice Kitty.

The title of TKD's LSU article says it all: Ultra-Stable Matter-Wave Gyroscopy with Counter-Rotating Vortex Superpositions in Bose-Einstein Condensates.

Sombrero Potential

Saturday, July 18, 2009

O Taste and See

For Adrianne Blue
London, England
Empress of Kisses


The world is
not with us enough.
O taste and see

the subway Bible poster said,
meaning The Lord, meaning
if anything all that lives
to the imagination's tongue,

grief, mercy, language,
tangerine, weather, to
breathe them, bite,
savor, chew, swallow, transform

into our flesh our
deaths, crossing the street, plum, quince,
living in the orchard and being

hungry, and plucking
the fruit.

--Denise Levertov

Thursday, July 16, 2009

A Book About Reality

Quantum theory is without doubt the most successful tool for manipulating matter that humans have ever possessed. Over scales ranging from quarks to quasars not one of quantum theory's predictions (some checked to 11 decimal places) has ever been falsified. Much of today's industry--silicon chips, lasers, hard drives, flash memory, for example--would be impossible without the precise understanding of matter's behavior that quantum theory provides.

But this overwhelming success comes with a peculiar price tag: Use this theory; lose Reality.

The deepest unsolved question of quantum theory is this: how can we properly conceive a model of the world for which quantum theory is a correct description? No one has posed the Quantum Reality Question better than UCSC professor Bruce Rosenblum who says: "Classical physics could explain the world but got some of the details wrong; quantum physics gets all the details right but can't explain the world."

Quantum theory describes the world in two ways, depending on whether it's being measured or not. When not measured, it's described by a wave of probabilities (called the psi-function); when it's measured, it turns into actual particles.

The Quantum Reality Question resolves itself into two parts:

1) The Interpretation Question: what does the psi-function actually stand for? What in the world is going on when we aren't making measurements?

2) The Measurement Problem: what happens during a measurement when (in the theory at least) waves turn into actual particles?

A successful Quantum Reality would tell us: 1) what the world is like when it's not looked at and 2) how the act of looking changes the unobserved world into the world we see.

In my book Quantum Reality: Beyond the New Physics I consider eight candidate models for a viable way of conceptualizing the world including Hugh Everett's Many-Universe Model (QR #4) and Werner Heisenberg's version (QR #8).

In Everett's Many-Universe Model, the psi-function describes not possibilities but actualities--Everything that can happen really does happen in one universe or another. That's what's going on in the world when you don't look. When you look, the universe you happen to be in splits into all possible outcomes of the measurement you chose to make but you are conscious of inhabiting only one of these branching paths. As preposterous as this model appears it ranks as the most detailed and mathematically consistent model of Quantum Reality yet put forth. The fact that such an outlandish model of reality is taken seriously by smart people is a measure of how desperate physicists have become in their quest to solve the Quantum Reality Question.

Heisenberg's Model proposes that there is only one world. But when nobody looks it's just a world of possibilities. Whenever somebody looks, one of these possibilities becomes actual. Heisenberg fails to tell us though, how the first real look happened in a world of pure possibility, nor does he say what a look looks like--that is, which sorts of interactions in the world qualify as "looks" and which are merely inconsequential dances of possibilities.

Unlike many popular physics books that trumpet the colorful successes of physics, Quantum Reality focuses single-mindedly on physics' most conspicuous failure--the Quantum Reality Question as the most embarrassing skeleton pushed way into the back of physics' secret closet. Quantum Reality explores in great detail a deep and glaringly unsolved problem located not in the hidden recesses of elementary particles or in some galaxy far away but right here at home--an unsolved mystery located literally everywhere we look.

None of the eight proposed Quantum Realities (and others since invented) feels right to me. No one today, I think, really knows how this world works. One easy way to fluster a physicist: ask what he/she thinks of the Measurement Problem.

Quantum Reality has been translated into German, Japanese and Portuguese. Nick gets about $1 in royalties for every copy sold. Recently made available (Dec 2011) as an E-book.

Beverly Rubik, PhD, in Italy

Wednesday, July 8, 2009

Betsy Rose Rasumny Herbert (1938-2002)

Happy Birthday, Betsy. You would have been 71 today had you not run away with Mr. Death.

Wife of Nick, mother of Khola, Betsy was above all a dancer. And for her, dance meant, not pretty movement, but the practice of being present in the moment. "Take everything that happens as it comes, " said Lao Tzu, "as something to animate, not to appropriate." Betsy lived that maxim to the max, and by her example, taught her friends, me among them, to more fully inhabit this lucky gift of embodiment in human form.

In our semi-rural community along the San Lorenzo River, Betsy was a prime mover in Home Birth, in Home Schooling and, at the end, in Home Death. For Betsy, birthing, teaching, dying and everything in between were all about "learning how to move energy". Her aim was striving to live fully, even as this body-gift was being taken from her.

Here's Betsy's obituary.

And here's one of Betsy's reflections on The Dance:


Stilling the air charged by previous dancers
Inhaling and lifting, look about,
search for someone to dance with.

Couples waiting to meet:
The old familiar: Will I be chosen?

Who will be my partner?
Will I find a mate?
Can we move together?
Will you share my space?

Grouping, hoping
See me
Hold me
Love me
I'm beautiful
O look, feel, sense
How it is we move together.

This says it all:
What our bodies do together.
Don't leave.

O let's have been connected before forever.
Let's not ever not touch.

Saturday, July 4, 2009



Do you believe in liberty?
Do you really understand how freedom feels?
Then cancel Independence Day
And wait your Stars and Stripes unfurl
Until there's not a single US base
On someone else's sacred soil.


(Visualize a Venezuelan Air Force Base
on the Hudson River upstream from NYC.)