Thursday, May 26, 201612:30 PM - 1:30 PMT-DO Conference Room (TA-3, Bldg 123 Room 121)|
The cost of achieving finite time adiabatic dynamics
Steve CampbellQueen’s University Belfast
Recent years have witnessed a surge of interest in the study of thermal nanomachines that
are capable of converting disordered forms of energy, such as heat, into useful work. It has
been shown for both classical and quantum systems that external drivings can allow a
system to evolve adiabatically even when driven in finite time, such techniques are
commonly known as shortcuts to adiabaticity (STA) .
It was suggested to use such external drivings to render the unitary processes of a
thermodynamic cycle quantum adiabatic, while being performed in finite time . This could
considerably augment the performance of nano-thermodynamic engines as work exchanges
are extremised by adiabatic protocols. However, implementing additional external driving
requires resources which affect the overall performance of the system .
We analyse the implications of considering the necessary power in applying these STA,
subsequently showing that this cost may outweigh the possible gains in work extraction for
slow enough processes due to the relative degree of adiabaticity in the dynamics, while for
relatively faster processes, the use STA can improve the work exchange. Furthermore, we
devise a general strategy that exploits the definition of work as a two-time measurement of
energy to improve the performance of work transfer. In particular, we show that it is possible
to achieve sizable energy savings by gathering information from the first measurement and
then applying a specifically tailored driving to the protocol. We apply our framework to
driving a critical many-body system through a quantum phase transition, where the closing
of the energy gap at the critical point makes the driving Hamiltonian of increasing complexity
 and show that this complexity necessitates a divergence in the cost of achieving finite
time adiabatic dynamics.
 Shortcuts to adiabaticity, E. Torrontegui, S. Ibáñez, S. Martínez-Garaot, M. Modugno, A. del Campo, D. Guéry-Odelin, A.
Ruschhaupt, Xi Chen, and J. G. Muga, Adv. At. Mol. Opt. Phys. 62, 117-169 (2013).
 More bang for your buck: Towards super-adiabatic quantum engines, A. del Campo, J. Goold, and M. Paternostro, Sci. Rep.
4, 6208 (2014).
 Cost of transitionless driving and work output, Yuanjian Zheng, Steve Campbell, Gabriele De Chiara, and Dario Poletti,
 Shortcut to Adiabaticity in the Lipkin-Meshkov-Glick Model, S. Campbell, G. De Chiara, M. Paternostro, G. M. Palma, and R.
Fazio, Phys. Rev. Lett. 114, 177206 (2015).
Host: Sebastian Deffner