NCTS (South)


DATE2015-03-05

TIME10:00

PLACER49223, Second Physics Building , NCKU

FIELDOther

SPEAKER Prof. Gentaro Watanabe - PODTECH & APCPT, Korea

TITLEQuantum measurements, quantum fluctuation theorems and their application: toward the quantum engineering using cold atomic gases

ABSTRACTCold atomic gases are novel quantum systems with high controllability and high measurability. With these unique features, they provide great opportunity to perform so-called "quantum engineering": controlling the quantum system in order to develop quantum devices such as quantum heat engines and heat pumps. As an important step toward understanding the properties and fundamental bounds of these devices which usually operate under non-equilibrium conditions, we recently started a new project on non-equilibrium quantum statistical mechanics. The discovery of the transient fluctuation theorems recognized as the Jarzynski equality [1] and the Crooks relation [2] is a recent large development in this field. These quantum fluctuation theorems assume that work is determined by projective energy measurements at the beginning and the end of the protocol. However, projective measurements are difficult to implement experimentally. This is a major obstacle to the direct verification of the transient fluctuation theorems in quantum systems. It is thus important to ask whether these projective measurements can be replaced with generalized measurements which could be easier to implement. First, we prove a kind of no-go theorem that only projective measurements can satisfy the Crooks relation for an arbitrary force protocol [3]. Then we show that, however, we can overcome this no-go theorem [4]. After I present these works, I will also discuss the future prospects in two topics: 1) towards the verification of the quantum fluctuation theorems in cold atomic gases and 2) the application of quantum fluctuation theorems for quantum heat engines.

[1] C. Jarzynski, Phys. Rev. Lett. 78, 2690 (1997).
[2] G. E. Crooks, Phys. Rev. E 60, 2721 (1999).
[3] B. P. Venkatesh, G. Watanabe, and P. Talkner, New J. Phys. 16, 015032 (2014).
[4] G. Watanabe, B. P. Venkatesh, and P. Talkner, Phys. Rev. E 89, 052116 (2014).