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Q3mini

Guides

  • Fermionic Quantum Computation
  • Q3: Symbolic Quantum Simulation
  • Quantum Information Systems
  • Quantum Many-Body Systems
  • Quantum Spin Systems

Tech Notes

  • About Q3
  • Q3: Quick Start
  • Quantum Fourier Transform
  • Quantum Information Systems with Q3
  • Quantum Many-Body Systems with Q3
  • Quantum Operations
  • Quantum Spin Systems with Q3
  • Quantum States
  • Quantum Teleportation
  • Quick Quantum Computing with Q3

Symbols

  • Basis
  • Boson
  • Bra
  • CNOT
  • ControlledGate
  • ExpressionFor
  • Fermion
  • Heisenberg
  • Ket
  • Let
  • Majorana
  • Matrix
  • Multiply
  • NambuGreen
  • NambuHermitian
  • NambuMatrix
  • NambuUnitary
  • Pauli
  • Phase
  • QuantumCircuit
  • Qubit
  • Qudit
  • RandomWickCircuitSimulate
  • Rotation
  • Species
  • Spin
  • SWAP
  • WickCircuit
  • WickEntanglementEntropy
  • WickEntropy
  • WickGreenFunction
  • WickJump
  • WickLindbladSolve
  • WickLogarithmicNegativity
  • WickMeasurement
  • WickMonitor
  • WickMutualInformation
  • WickNonunitary
  • WickSimulate
  • WickState
  • WickUnitary

Overviews

  • The Postulates of Quantum Mechanics
  • Quantum Algorithms
  • Quantum Computation: Models
  • Quantum Computation: Overview
  • Quantum Error-Correction Codes
  • Quantum Information Theory
  • Quantum Noise and Decoherence
QuantumMob`Q3mini`
WickEntanglementEntropy
​
WickEntanglementEntropy
[grn,[
k
1
,
k
2
,…]]
returns the entanglement entropy between the subsystem consisting of fermion modes
{
k
1
,
k
2
,…}⊂{1,2,…,n}
in the
Wick state
characterized by
n×n
matrix
grn
of single-particle Green's functions.
​
​
WickEntanglementEntropy
[
NambuGreen
[{grn,anm}],{
k
1
,
k
2
,…}]
or
WickEntanglementEntropy
[{grn,anm},[
k
1
,
k
2
,…}]
​ returns the entanglement entropy in the
Wick state
characterized by
n×n
matrices
grn
and
anm
of normal and anomalous Green's functions, respectively.
​
​
WickEntanglementEntropy
[state,{
k
1
,
k
2
,…}]
is equivalent to
WickEntanglementEntropy
[
WickGreenFunction
[state,{
k
1
,
k
2
,…}],{
k
1
,
k
2
,…}]
for Wick
state
.
​
​
WickEntanglementEntropy
[{
k
1
,
k
2
,…}]
is an operator form of
WickEntanglementEtropy
to be applied to Green's functions or
Wick state
s.
​
Details and Options

Examples  
(1)
Basic Examples  
(1)
Set the number of fermion modes to consider.
In[1]:=
$n=6;
Construct a Wick state. Make sure that it is normalized because many functions such as
WickGreenFunction
and
WickEntanglementEntropy
expect a normalized state as input.
In[2]:=
SeedRandom[347];
In[3]:=
ws=RandomWickState[$n]
Out[3]=
WickState
Modes: 6
Prefactor: 1

In[4]:=
Norm[ws]
Out[4]=
1
Take the half of the system as one subsystem.
In[5]:=
aa=Range[$n/2]
Out[5]=
{1,2,3}
Calculate the entanglement entropy.
In[6]:=
ent=WickEntanglementEntropy[ws,aa]
Out[6]=
1.8867
You can also calculate the entanglement entropy using the Green's function.
In[7]:=
gg=WickGreenFunction[ws]//Chop;​​gg//ArrayShort
Out[7]=

0.301477
0.0656129+0.0235416
-0.147069+0.00887366
0.0479388-0.128885
…
0.0656129-0.0235416
0.353766
0.0535252+0.0640552
0.082095+0.0898905
…
-0.147069-0.00887366
0.0535252-0.0640552
0.470892
-0.100396+0.0200553
…
0.0479388+0.128885
0.082095-0.0898905
-0.100396-0.0200553
0.477254
…
…
…
…
…
…
,
0
-0.0265307+0.140911
-0.126166+0.00947692
-0.116034-0.0215489
…
0.0265307-0.140911
0
-0.250196-0.0528364
0.111321+0.153215
…
0.126166-0.00947692
0.250196+0.0528364
0
0.204128-0.156129
…
0.116034+0.0215489
-0.111321-0.153215
-0.204128+0.156129
0
…
…
…
…
…
…

In[8]:=
new=WickEntanglementEntropy[gg,aa]
Out[8]=
1.8867
In[9]:=
ent-new//Chop
Out[9]=
0
SeeAlso
WickEntropy
 
▪
WickMutualInformation
 
▪
WickLogarithmicNegativity
 
▪
WickGreenFunction
 
▪
WickState
TechNotes
▪
VonNeumann Entropy
▪
Quantum Information Theory
▪
Quantum Information Systems with Q3
▪
Quantum Many-Body Systems with Q3
▪
Q3: Quick Start
RelatedGuides
▪
Fermionic Quantum Computation
▪
Quantum Many-Body Systems
▪
Q3: Symbolic Quantum Simulation
RelatedLinks
▪
P. Calabrese and J. Cardy (2004)
, Journal of Statistical Mechanics, P06002 (2004), "Entanglement entropy and quantum field theory."
▪
I. Peschel (2003)
, Journal of Physics A, 36, 205 (2003), "Calculation of reduced density matrices from correlation functions."
▪
Mahn-Soo Choi (2022)
, A Quantum Computation Workbook (Springer).
""

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