Category Archives: News

“Nature, you instruct me.”

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“Settle thy studies.”

Alone in his workroom, a student contemplates his future. Piles of books teeter next to him. Boxes line the walls; and glass vials, the boxes. Sunbeams that struggle through the stained-glass window illuminate dust.

The student’s name is Faust. I met him during my last winter in college, while complementing Physics 42: Introductory Quantum Mechanics with German 44: The Faust Tradition. A medieval German alchemist, Faust has inspired plays, novels, operas, the short story “The Devil and Daniel Webster” about an American Congressman, and the film “Bedazzled” starring Brendan Frasier.

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The Faust tradition in popular culture. Mephistopheles is the demon who buys Faust’s soul. (http://xkcd.com/501/)

As I wondered what to pursue a PhD in, so (roughly speaking) did Faust. In plays by Christopher Marlowe and Johann Wolfgang von Goethe, Faust wavers among law, theology, philosophy, and medicine. You’ve probably heard what happens next: Faust chooses sorcery, conjures a demon, and bargains away his soul. Hardly the role model for a college student. I preferred to keep my soul, though Maxwell’s demon had stolen my heart.

A few decades after Goethe penned Faust, English physicist James Maxwell proposed a thought experiment. Consider a box divided into two rooms, he wrote, and a demon controlling the door between the rooms. Since others have explained Maxwell’s paradox, I won’t parrot them. Suffice to say, the demon helps clarify why time flows, what knowledge is, and how information relates to matter. Quantum-information physicists, I learned in a seminar after German 44, study Maxwell’s demon. Via the demon, experiment, and math, QI physicists study the whole world. I wanted to contemplate the whole world, like Goethe’s Faust. By studying QI, I might approximate my goal. Faust, almost as much as my QI seminar, convinced me to pursue a PhD in physics.

Fast forward two years. Someone must have misread my application, because Caltech let me sign my soul to its PhD program. I am the newest Preskillite. Or Preskillnik. Whichever term, if either, irks my supervisor more.

For five years, I will haunt this blog. (Spiros will haunt me if I don’t haunt it.) I’ll try to post one article per month. Pure quantum information occupies me usually: abstract math that encodes physical effects, like entropy (a key to why time flows), decoherence (a system’s transformation from quantum to ordinary), and entanglement (one particle’s ability to affect another, instantaneously, from across a room).

In case I wax poetic about algebra, I apologize in advance. Apologies if I write too many stories about particles in boxes. In addition to training a scientist’s lens on atoms, I enjoy training it on science, culture, and communities. Tune in for scientists’ uses (and abuses) of language, why physics captivates us, and the bittersweetness of representing half our species in a roomful of male physicists (advantage: I rarely wait in line to use a physics department’s bathroom).

As I prepare to move to Caltech, a Faust line keeps replaying in my mind. It encapsulates my impression of a PhD, though written 200 years ago: “Nothing I had; and yet, enough for youth—/ delight in fiction, and the thirst for truth.”

Pleasure to meet you, Quantum Frontiers. Drink with me.

Topological insulator trio recognized by 2013 Physics Frontiers Prize

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I was excited to hear that Charlie Kane, Laurens Molenkamp and Shoucheng Zhang were among the recipients of the 2013 Physics Frontiers Prize. Their seminal works both theoretically predicting and experimentally discovering the topological insulator have profoundly influenced the direction of condensed matter physics over the past few years and have shaped my own research agenda at Caltech.

I first learned about the topological insulator from a talk Charlie Kane delivered at the 2006 American Physical Society March Meeting. It was around this time that graphene was exploding onto the scene following Andre Geim and Konstantin Novoselov’s demonstration that single sheets of it could be peeled from graphite using Scotch tape. Inspired by the highly unconventional charge transport properties that were being measured from graphene, Charlie had begun to think about whether its spin transport properties might also yield surprises. The huge surprise, as Charlie would reveal in his talk, was that graphene could theoretically exhibit a quantum spin Hall effect in which spin-polarized charge carriers flow without dissipation along the edges of an electrically insulating material. Such quantum spin Hall insulators (later renamed the 2D topological insulator), as Charlie and his colleague Eugene Mele proved, are a phase of matter distinct from ordinary electrical insulators by virtue of a quantum entanglement of its electrons.
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Ignacio Cirac and Peter Zoller get what they deserve

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Ignacio Cirac, Dave Wineland, and Peter Zoller receiving the 2010 Franklin medal.

Ignacio Cirac, Dave Wineland, and Peter Zoller receiving the 2010 Franklin medal.

A good thing about a blog is that when my friends win prizes I have the opportunity to say nice things about them. This seems to be happening a lot lately (Kitaev, Wineland, Kimble, Hawking, Polchinski, …).

Today’s very exciting news is that Ignacio Cirac and Peter Zoller have won the 2013 Wolf Prize in Physics “for groundbreaking theoretical contributions to quantum information processing, quantum optics, and the physics of quantum gases.”
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Fundamental Physics Prize Prediction: Polyakov

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Rushing to produce a congratulatory post for Stephen Hawking yesterday, I didn’t mention the other big news regarding the Fundamental Physics Prize. Joe Polchinski, Sasha Polyakov, Charlie Kane, Laurens Molenkamp, and Shoucheng Zhang have received the 2013 Physics Frontiers Prize, making them eligible for the Fundamental Physics Prize to be announced on March 20. The New Horizon in Physics Prize (for young physicists) has been awarded to Niklas Beisert, Davide Gaiotto, and Zohar Komargodski. And another “special” $3M Prize, shared by seven people, appropriately recognizes the discovery of the Higgs boson.

The selection committee did a good job.

Joe Polchinski

Joe Polchinski

Joe Polchinski was a Caltech undergrad, class of 1975 (before my time here). I first met Joe in 1982 when he arrived as a postdoc at Harvard, where I was then on the faculty, and it did not take long for me to recognize his genius. I was teaching a course that fall on advanced quantum field theory, and Joe sat in, at least for a while. One of my lectures was about renormalizability, and I talked about how the renormalization group can organize and simplify the horrible combinatoric task of taming the overlapping divergences in Feynman diagrams to all orders of perturbation theory. I had learned this idea from Curt Callan‘s wonderful 1975 Les Houches Summer School Lectures.
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Stephen Hawking wins $3M Milner Prize

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The official announcement won’t come until tomorrow, but The New York Times is reporting that Stephen Hawking will receive a “special” $3M Prize from Yuri Milner’s Fundamental Physics Prize Foundation.

This is fantastic news! I assume the Prize recognizes Stephen’s great discovery that black holes radiate, one of the most transformative developments in theoretical physics during my lifetime. That’s just one of Stephen’s many important contributions. And of course his supreme skill as a popularizer and the unparalleled courage he displays in response to his disability have made him the most famous living scientist in the world. Congratulations, Stephen!

Stephen has a long-standing relationship with Caltech. He spent a sabbatical year here during 1974-75, when he wrote his famous paper formulating the black hole information paradox, and he has made more or less annual extended visits to Caltech since the 1990s. Stephen and I had many memorable discussions about black holes over the years, culminating when he conceded a bet, for which I received far more attention than I deserved. I’ve been proud to be Stephen’s friend for the past 30 years, and we’ve shared a lot of laughter.

With Kip Thorne and Stephen Hawking, 2005.

With Kip Thorne and Stephen Hawking, 2005.


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Jeff Kimble wins 2013 Herbert Walther Award

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Prof. Kimble knew Prof. Walther personally and has a profound respect for him and his accomplishments. He is greatly honored by this award.

Prof. Kimble knew Prof. Walther personally and has profound respect for him and his accomplishments. He is greatly honored by this award.

H. Jeff Kimble, William L. Valentine Professor of Physics at Caltech, is the recipient of the 2013 Herbert Walther award. This award is jointly made by the Deutsche Physikalische Gesellschaft (DPG, the German Physical Society) and the Optical Society of America (OSA), and is presented by each society in alternate years.

The award recognizes Jeff’s “pioneering experimental contributions to quantum optics, cavity quantum electrodynamics, and quantum information science“. Many of the achievements that have taken place in the Kimble group deserve their share of this prize. Among the most impacting ones are the photon antibunching, the demonstration of a quantum phase gate to perform quantum logic operations, nonlinear optics with a single atom strongly coupled to single photons in an optical cavity, the one-atom laser in the regime of strong coupling, a single photon source made by an atom inside a cavity, and entanglement between atomic ensembles.

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The TV Frontier

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Hello, my name is Tim Blasius and I am a physics graduate student at Caltech.  I recently appeared in a comedy bit on the TV show Conan, where I corrected Conan O’Brien’s physics.  I have been asked to share a few words describing this experience.

As with any story involving unbridled success, it begins as a tale of unnoticed, under-appreciated  and nearly unending hard work – I usually watch the show Conan during dinner with my fiancé.  Accordingly, I have seen many segments called “fan corrections” where Conan viewers submit YouTube videos explaining mistakes that they believe Conan has made on the show.  Some are nerdy and funny like the one where viewers pointed out that Conan used a red-tailed hawk call instead of a bald eagle call.  I was like a crocodile lurking in the water waiting for Conan to make a mistake in my expertise.  Then, like a woefully ignorant antelope sipping from the river Nile, Conan made a physics mistake when mocking Felix Baumgartner’s free fall, and I, being the bloodthirsty physics predator that I am, snapped the jaws of immutable truth around his naïve self.

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Individual quantum systems

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When I went to school in the 20th century, “quantum measurements” in the laboratory were typically performed on ensembles of similarly prepared systems. In the 21st century, it is becoming increasingly routine to perform quantum measurements on single atoms, photons, electrons, or phonons. The 2012 Nobel Prize in Physics recognizes two of the heros who led these revolutionary advances, Serge Haroche and Dave Wineland. Good summaries of their outstanding achievements can be found at the Nobel Prize site, and at Physics Today.

Serge Haroche developed cavity quantum electrodynamics in the microwave regime. Among other impressive accomplishments, his group has performed “nondemolition” measurements of the number of photons stored in a cavity (that is, the photons can be counted without any of the photons being absorbed). The measurement is done by preparing a Rubidium atom in a superposition of two quantum states. As the Rb atom traverses the cavity, the energy splitting of these two states is slightly perturbed by the cavity’s quantized electromagnetic field, resulting in a detectable phase shift that depends on the number of photons present. (Caltech’s Jeff Kimble, the Director of IQIM, has pioneered the development of analogous capabilities for optical photons.)
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Alesha

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An excerpt from my notes (including a misspelling of “repetition”) taken at Alexei Kitaev’s seminar during his first visit to Caltech in 1997. That was a very exciting day.

In 1997, I had some disposable funding as part of a quantum computing project, and decided to seize the opportunity to bring an interesting visitor to Caltech. But whom to invite? Chris Fuchs, then a postdoc at Caltech who seemed to know everybody working on quantum computing, reported that Richard Jozsa, while attending a conference in Japan, had met a remarkable Russian from the Landau Institute named Alexei Kitaev.
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