Category Archives: Theoretical highlights

Highlighting theoretical progress at IQIM.

How to build a teleportation machine: Teleportation protocol

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Damn, it sure takes a long time for light to travel to the Pegasus galaxy. If only quantum teleportation enabled FTL Stargates…

I was hoping to post this earlier, but a heavy dose of writer’s block set in (I met a girl, and no, this blog didn’t help — but she is a physicist!) I also got lost in the rabbit hole that is quantum teleportation. My initial intention with this series of posts was simply to clarify common misconceptions and to introduce basic concepts in quantum information. However, while doing so, I started a whirlwind tour of deep questions in physics which become unavoidable as you think harder and deeper about quantum teleportation. I’ve only just begun this journey, but using quantum teleportation as a springboard has already led me to contemplate crazy things such as time-travel via coupling postselection with quantum teleportation and the subtleties of entanglement. In other words, quantum teleportation may not be the instantaneous Stargate style teleportation you had in mind, but it’s incredibly powerful in its own right. Personally, I think we’ve barely begun to understand the full extent of its ramifications.

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How to build a teleportation machine: Intro to entanglement

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Oh my, I ate the whole thing again. Are physicists eligible for Ben and Jerry’s sponsorships?

I’m not sure what covers more ground when I go for a long run — my physical body or my metaphorical mind? Chew on that one, zen scholar! Anyways, I basically wrote the following post during my most recent run, and I also worked up an agressive appetite for Ben and Jerry’s ice cream. I’m going to reward myself after writing this post by devouring a pint of “half-baked” brown-kie ice cream (you can’t find this stuff in your local store.)

The goal of this series of blog posts is to explain quantum teleportation and how Caltech built a machine to do this. The tricky aspect is that there are two foundational elements of quantum information that need to be explained first — they’re both phenomenally interesting in their own right, but substantially subtler than a teleportation device, so the goal with this series is to explain qubits and entanglement at a level which will allow you to appreciate what our teleportation machine does (and after explaining quantum teleportation, hopefully some of you will be motivated to dive deeper into the subtleties of quantum information.) This post will explain entanglement.
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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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An intellectual tornado

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Hello?… The first thing I remember feeling moments later was panic.

Five years before that day, I was a graduating senior at MIT pursuing a Bachelor of Science in Mathematics with Computer Science (18C for all the fellow nerds out there). I had been close to some of the most brilliant people I have ever met, like my undergraduate adviser Michael Sipser and my undergraduate research mentor in bioinformatics, Bonnie Berger. I had applied to several graduate schools to study mathematics, but had been summarily rejected by most of them. It was a humbling experience, which ultimately led me to the day I got the call. I remember clearly what day it was: February 6th, 2008. I was eating breakfast with two friends at a local diner in Davis, CA. Yes, the one place which had enthusiastically accepted me to their Ph.D. program was the Mathematics Department at UC Davis. In fact, being an international student from Greece, and given the tight State budget of California at the time (all the time), it was a miracle that UC Davis said yes. True, I had a good GPA and lots of research experience at MIT, but I did not have any direction. I did not apply to work with any particular Professor, I just applied by school name and reputation. And if it weren’t for Prof. Berger’s suggestion to apply to UC Davis, I would have applied to the top 5 graduate schools in Applied Mathematics and would be trading stocks in New York right now. I was naive.
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More to come

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John Wheeler. Photo by the New York Times/Redux.

As a sophomore at Princeton I took a class called Honors Physics from a man named Johnny Wheeler. He wore a suit and tie to class, loved explosions, and created vivid art in real time with colored chalk. Implausibly old, he had worked on nuclear fission with Niels Bohr. He was 61.

The lectures were long on inspiration and short on information about how to do the homework. I was in awe of Wheeler. Some students thought he sucked.

One day I arrived late to find Wheeler conducting a poll. We were voting on the future of science: is there “more to come” or “less to come”? I don’t remember the count, but “more to come” won handily. Wheeler was pleased.

Later, at a student-faculty lunch, Wheeler seemed troubled. He had been asked to explain the essence of quantum mechanics in five words or less, and was stumped. Frank Calaprice, a nuclear physicist within earshot, interjected helpfully, “What we expect to measure?” I was silent.

The question was absurd. It was fascinating. I still think about it. I can’t answer it.

This year I taught a course on quantum statistical physics to Caltech sophomores. I wore khakis and always used the white chalk. Though I’m 59, few students seemed awed. Some thought I sucked. Maybe I did sometimes.

Johnny Wheeler never blogged. If he had, some readers would have been awed. Some would have thought he sucked.

But Johnny would not have reminisced about a class he took 40 years ago. He knew there was more to come.

Welcome to Quantum Frontiers! We hope that the posts to come will be long on inspiration, even if short on information about how to do your homework. Enjoy!