scholarly journals Dissipative environment may improve the quantum annealing performances of the ferromagnetic p -spin model

2018 ◽  
Vol 97 (2) ◽  
Author(s):  
G. Passarelli ◽  
G. De Filippis ◽  
V. Cataudella ◽  
P. Lucignano
Proceedings ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 26
Author(s):  
Gianluca Passarelli ◽  
Giulio Filippis ◽  
Vittorio Cataudella ◽  
Procolo Lucignano

We discuss the quantum annealing of the fully-connected ferromagnetic p-spin model in a dissipative environment at low temperature. This model, in the large p limit, encodes in its ground state the solution to the Grover’s problem of searching in unsorted databases. In the framework of the quantum circuit model, a quantum algorithm is known for this task, providing a quadratic speed-up with respect to its best classical counterpart. This improvement is not recovered in adiabatic quantum computation for an isolated quantum processor. We analyze the same problem in the presence of a low-temperature reservoir, using a Markovian quantum master equation in Lindblad form, and we show that a thermal enhancement is achieved in the presence of a zero temperature environment moderately coupled to the quantum annealer.


2018 ◽  
Vol 98 (4) ◽  
Author(s):  
Yuki Susa ◽  
Yu Yamashiro ◽  
Masayuki Yamamoto ◽  
Itay Hen ◽  
Daniel A. Lidar ◽  
...  

2019 ◽  
Vol 100 (2) ◽  
Author(s):  
G. Passarelli ◽  
V. Cataudella ◽  
P. Lucignano
Keyword(s):  

2020 ◽  
Vol 101 (2) ◽  
Author(s):  
Gianluca Passarelli ◽  
Ka-Wa Yip ◽  
Daniel A. Lidar ◽  
Hidetoshi Nishimori ◽  
Procolo Lucignano
Keyword(s):  

Author(s):  
M. M. Glazov

The discussion of the electron spin decoherence and relaxation phenomena via the hyperfine interaction with host lattice spins is presented here. The spin relaxation processes processes limit the conservation time of spin states as well as the response time of the spin system to external perturbations. The central spin model, where the spin of charge carrier interacts with the bath of nuclear spins, is formulated. We also present different methods to calculate the spin dynamics within this model. Simple but physically transparent semiclassical treatment where the nuclear spins are considered as largely static classical magnetic moments is followed by more advanced quantum mechanical approach where the feedback of electron spin dynamics on the nuclei is taken into account. The chapter concludes with an overview of experimental data and its comparison with model calculations.


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