# Viacheslav Belavkin

I am sad to report that Viacheslav Belavkin recently passed away. One of the rarified few who made important contributions to quantum information in the 1970’s, Belavkin’s work was and is very significant in both physics and mathematics.
Belavkin won the Main State Prize of Russia (formerly the Lenin prize) in 1996, jointly with Stratanovich, for his contributions to stochastic calculus and the theory of quantum measurement.
I only met Belavkin once, while he was visiting the Perimeter Institute. He was dining alone, and had just finished dinner and was about to pay, so he told the server put the bill on the tab for Belavkin. Overhearing this, I turned to him and said “Oh, you’re Belavkin!” He was clearly pleased that I knew who he was, and over a beer he shared with me some of the very interesting history of the early days of quantum information theory. You can read for yourself Belavkin’s perspective on the early days of the field through his potted autobiography. (The link is to a web cache, since sadly the University of Nottingham has taken down his personal webpage.)
It was clear from my conversation with him that he was the quintessential jaded ex-Soviet scientist who had seen everything done 10 years ahead of its rediscovery in the West. He wasn’t very modest about his own discoveries, either. I distinctly remember him saying the following, “My first paper on quantum information theory was in 1972. And Stratanovich had some in the 60’s.” To his great credit, though, he was essentially correct! Much of his work was rediscovered in the 90’s, often in less generality.
Chris Fuchs told me a classic story about Belavkin, which I’ll recall as best I can. Sometime in the 90’s, Chris was at a conference along with many smart people working on continuous measurement and feedback control of quantum systems. When it was Belavkin’s turn to talk, he calmly took the chalk and began to recap the talks from the morning session where people had been presenting their recent work.
“This morning we heard a talk by Prof. Smith in which he proved the following theorem.”  Belavkin calmly scrawled the statement of the theorem on the board, in a formal style,

Theorem 1 [Smith, 1995]. For all $x$, there exists a $y$ such that

He continued, “Then we heard a talk by Prof. Jones, where he proved the following.”  Once more, he carefully wrote the statement of the theorem on the board, just below the first one.  “And finally we heard from Prof. Brown, who demonstrated this theorem.”  Again, he patiently wrote the formal statement of the theorem on the board, with the name and date for attribution.
Belavkin paused for dramatic effect, then began writing new dates to the right of the theorems.  “In 1972 I proved Theorem 1.  In 1976 I proved Theorem 2.  And in 1985 I proved Theorem 3.  Now we will hear about some new results.”
Here is the notice of his passing from the University of Nottingham. I hope that they will make his old webpage available again.

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### 7 Responses to Viacheslav Belavkin

1. Daniel Burgarth says:

At a conference end of 2011 Belavkin gave a talk where he humorously remarked that he’d tried to get his name attached to the master equation for decades; but, in being unsuccessful, was now considering to change his own name to “Master”.

2. Frank says:

Belavkin indeed made seminal contributions to quantum measurement and control theory in the 70’s and 80’s, and it seems that he felt that he did not get enough recognition for that. In his talk at QCMC2006 in Calgary, he made a funny remark : “The point of proving theorems in physics is the fact that it makes further elementary experiments on the topic superfluous” (I do not remember his exact phrasing however)

3. John Sidles says:

We still have with us another respect-worthy pioneer of quantum measurement theory: Michael Mensky

4. John Sidles says:

Yikes — my brief encomium to another pioneer of quantum measurement theory, namely Michael Mensky, has disappeared from Quantum Pontiff.
Although some of Mensky’s recent writings are (to an indeterminate degree) unorthodox, the work summarized in Mensky’s monograph Continuous Quantum Measurements and Path Integrals (1993) is lucidly presented, and has shown itself to have many practical applications, and is entirely worthy of our appreciation and respect.

5. Josh says:

â€œTheory helps to avoid unnecessary experimentsâ€
â€“ V. P. Belavkin (during his QCMC 2008 talk).
â€œExperiment helps to avoid unnecessary theoriesâ€
â€“ M. Aspelmeyer (responds in his QCMC 2008 talk).
Apparently after Markusâ€™ talk Slava approached him and said: â€œbut I said ‘good theoryâ€™…â€. Private communication 2009 M. Aspelmeyer.

6. Gerardo says:

Thanks a lot for this post!! I had written a longer post but i can’t see it published.. just want to report anyway that Slava’s page is back on with a tribute and the biography you linked. thanks again!

7. John Sidles says:

A minor typo: Belavkin won the Russian Federation State Prize (1996) together with Ruslan Stratonovich (not “Stratanovich”).