[f(k)] Colloquium Sorin Paraoanu TODAY 10:15 FYS1

[Ilari Maasilta]

Dear all,

welcome to this week's colloquium.
  (even those of you stressing about the Academy deadline, if you 
haven't submitted yet: take a break, and relax your nerves at the 
colloquium!)


TODAY  30 Sept, at 10:15 in FYS1 Speaker:**Sorin Paraoanu, Aalto 
University***
Title:    **********Superconducting circuits as a tool for exploring the 
foundations of quantum physics*****

Abstract:

During the last decade, remarkable developments in the technology of 
Josephson junctions have enabled us to
fabricate superconducting circuit elements that behave like artificial 
atoms. The properties of these atoms (called superconducting qubits)  
can be - to a certain degree of extend  - designed at will. The qubits 
can also be coupled to each other, which opens the possibility of 
simulating many-body systems and performing quantum gates.

In this talk I will depart however from presenting the mainstream ideas 
of quantum computing.
Instead, I will argue that the qubit technology allows us to perform 
experiments that are relevant for other fundamental aspects of quantum 
theory. I will start by presenting  some experimental and theoretical 
results related to the so-called Autler-Townes effect, showing  that a 
superconducting phase qubit can be operated as a three-level system. 
Then I will show that - contrary to what we might learn from some 
textbooks - quantum measurements can be reversed, and the qubit 
measurement technique provides for a rather clear demonstration of this 
measurement "undoing". This opens up the intriguing question of wheather 
it is possible to extract information from a single quantum system by a 
sequence of  measurements and reversals. The answer turns out to be "no" 
- had it been a "yes", the 100-year old "peaceful coexistence" between 
quantum physics and relativity would be over. In the end, I will discuss 
the prospects for using these systems for testing cosmological effects 
such as Hawking radiation.




Best regards,

Kari Eskola and Ilari Maasilta

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