CBPF prize award colloquium: Stephen P. Walborn

Edit 27.08.2015. The colloquium given by Steve is already online!


Tomorrow (25.09.15) CBPF will award the “CBPF prize” to Stephen Patrick Walborn… I mean, to Steve. Actually, you should pronounce his name as “Xtiiive”, as dictated by the carioca accent that he speaks with mother-tongue fluency. Stephen was born in USA; he then became Steve, when he moved to Belo Horizonte to do his PhD; and finally he turned into “Xtiiive”, spending his time in between the lab at the Federal University of Rio de Janeiro (UFRJ) and the Posto 6 in Copacabana… with occasional stops at Pavão Azul.

The award to Steve is more than deserved, it is natural. I’ve known Steve for more than 10 years by now, and if something changed during this time was… that I got older. Steve didn’t. As I wrote in the acknowledgement of my PhD thesis in 2006, and which is still true nowadays, Steve is tireless. The text I wrote said something along the lines “Steve is an inexhaustible source of ideas, causing me to be almost embarrassed when he would tell me at ten o’clock in the morning (after he had gone to the beach, to the gym, made an experiment, written an article and revised another – phew!) that the idea he had told me in the previous day had already been published by someone else but he had already thought of two other possibilities, for which he had already made some small calculations”. This is so true, that we made it into a framed picture which now hangs over his table in the lab… (okay, there is a Rocky Balboa picture in his office as well)

SteveOffice SteveQuadro

And that is just one aspect of Steve. Because he is not only a great physicist, with more than 80 articles, collecting more than 3300 citations (see his Google Scholar and cv), member of the Brazilian Academy o Sciences, professor at the physics department of UFRJ, head of the quantum optics lab, advisor of various students, mentor for many of us… but he does all that with style. Seriously, the guy is cool. Check it out.

Steve Rei do Rio

Steve taking part in a stand up paddle competition in 2014, when he became “o Rei do Rio”.

Sure he is the main author of the first direct measurement of entanglement (by the way this is the reason he will be given the CBPF prize), but he is also “o Rei do Rio” (the king of Rio)! Sure he is the brain behind the use of the Talbot effect to do quantum computation, but he is also the founding father of the WhatsApp group “Os Fulanos de Talbot” and inventor of the already worldwide known expression “Talbôtimo”.

Steve combines in a unique way a profound knowledge of physics, with an almost childish passion for new ideas and for enjoying life. It is a great privilege for us to have Steve around, specially as such a good friend.

Now that is clear why awarding Steve the CBPF prize is natural, don’t miss the chance of getting inspired by Steve and, of course, to congratulate him. The details of this special colloquium are below. See you there.

Congratulations and thank you very much Xtiiive!


Awardee: Stephen P. Walborn (IF-UFRJ)

Seminar title: Medida Direta de Emaranhamento Quântico

Coordinates: 25th of August, 16h. In the auditorium located at CBPF’s 6th floor.

Summary: O emaranhamento quântico tem sido um aspecto controverso da Física Quântica desde 1935, quando Einstein, Podolsky e Rosen postularam que esta “fantasmagórica ação à distância” era apenas uma consequência teórica de uma teoria incompleta. Na década de 1960, John Bell mostrou que a existência (ou não) de correlações mais fortes do que as correlações clássicas, tais como emaranhamento, poderia ser testada experimentalmente. Desde então, quase todos os resultados experimentais parecem confirmar a existência de emaranhamento na natureza.

Nos últimos vinte anos o emaranhamento vem sendo visto não só como um aspecto fundamental da teoria quântica, como também um recurso que poderia ser utilizado para realizar tarefas que não podem ser executadas dentro das leis da física clássica. A criptografia quântica e o teletransporte prometem revolucionar o modo de transmissão de informações secretas. Enquanto os computadores quânticos permitirão a solução mais rápida de vários importantes problemas computacionais. Estas aplicações estão vinculadas frequentemente a conhecimentos fundamentais sobre o papel da informação e das correlações no mundo quântico.

Já que o emaranhamento é um recurso, será que poderia ser quantificado? Esta pergunta foi respondida positivamente e várias métricas têm sido propostas. Em geral, os quantificadores de emaranhamento são funções da matriz de densidade e não correspondem diretamente a um observável físico que pode ser medido no estado quântico. No entanto, em 2004, foi mostrado que o emaranhamento pode ser medido diretamente se temos acesso a duas cópias do estado quântico simultaneamente. Em 2006, a primeira medição direta de emaranhamento quântico foi realizada no Laboratório de Ótica Quântica do Instituto de Física da UFRJ. Nesta palestra, discutirei este experimento e mencionarei brevemente alguns resultados importantes que têm sido obtidos desde então.


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