Physics Letters B 797 (2019) 134898
Contents lists available at ScienceDirect
Physics Letters B
www.elsevier.com/locate/physletb
More on complexity in finite cut off geometry
S. Sedigheh Hashemi
a
, Ghadir Jafari
a
, Ali Naseh
a
, Hamed Zolfi
a,b,∗
a
School of Particles and Accelerators, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran, Iran
b
Department of Physics, Sharif University of Technology, P.O. Box 11365-9161, Tehran, Iran
a r t i c l e i n f o a b s t r a c t
Article history:
Received
27 June 2019
Received
in revised form 26 August 2019
Accepted
26 August 2019
Available
online 29 August 2019
Editor:
N. Lambert
It has been recently proposed that late time behavior of holographic complexity in a uncharged black
brane solution of Einstein-Hilbert theory with boundary cut off is consistent with Lloyd’s bound if we
have a cut off behind the horizon. Interestingly, the value of this new cut off is fixed by the boundary
cut off. In this paper, we extend this analysis to the charged black holes. Concretely, we find the value of
this new cut off for charged small black hole solutions of Einstein-Hilbert-Maxwell theory, in which the
proposed bound on the complexification is saturated. We also explore this new cut off in Gauss-Bonnet-
Maxwell
theory.
© 2019 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license
(http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP
3
.
1. Introduction
In recent years, amazing and interesting connections have been
discovered between theoretical quantum information theory and
quantum gravity. These connections have been provided through
AdS/CFT duality by which certain quantities in dual quantum field
theory can be related to certain quantities in the bulk spacetime.
The leading example of such relation is the Ryu-Takayanagi pro-
posal
which provides a geometrical realization of entanglement en-
tropy
in a dual CFT [1]. The next example is the Susskind proposal
[2]by which quantum computational complexity of a boundary
state is dualized to a special portion of spacetime. Interestingly
enough, this proposal can be used to understand the rich geomet-
ric
structures that exist behind the horizon and also to construct
the dual operators that describe the interior of a black hole. In this
way one can, hopefully, resolve the black hole information paradox
which has been a focus of attention over the past years [3–9]. This
essential property of complexity comes from this fact that even af-
ter
the boundary theory reached thermal equilibrium it continues
to increase.
The
complexity of a quantum target state (systems of qubits)
is essentially defined as the minimum number of gates one needs
to act on a certain reference state to produce approximately the
desired target state [10,11]. In this notion, the gates are unitary op-
*
Corresponding author.
E-mail
addresses: hashemiphys@ipm.ir (S.S. Hashemi), ghjafari@ipm.ir (G. Jafari),
naseh@ipm.ir (A. Naseh), hamed.Zolfi@physics.sharif.edu (H. Zolfi).
erators which can be taken from some universal set. For instance,
one may be asked how hard it is to prepare the ground state of
a local Hamiltonian, which generally is an entangled state, from
a reference state which is spatially factorisable. This suggests that
there might exist a deep relation between complexity of preparing
a quantum state and the entanglement between degrees of free-
dom
in that quantum state.
To
describe the quantum complexity of states in boundary QFT,
two holographic proposals have been developed, complexity = vol-
ume
(CV) conjecture [2,12] and complexity=action (CA) conjecture
[13,14]. In the CA conjecture, which is the main focus of this
manuscript, the quantum complexity of a state, C
A
, is given by
C
A
=
I
WDW
π
¯
h
, (1)
where I
WDW
is the on-shell gravitational action evaluated on a cer-
tain
subregion of spacetime known as the Wheeler-DeWitt (WDW)
patch and we will set
¯
h = 1from now on. It is worth noting that
the intersection of WDW patch with the future interior determines
completely the late time behavior of complexity growth rate [15]
which
is in agreement with Lloyd’s bound [16]. The Lloyd’s bound
says that the upper bound on rate of complexity growth (for un-
charged
systems) is twice the energy of system and this energy in
the holographic set up is actually the mass of black hole. According
to the holographic calculations at late times
dC
A
dt
=2M
BH
, (2)
https://doi.org/10.1016/j.physletb.2019.134898
0370-2693/
© 2019 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by
SCOAP
3
.