<s>
Quantum	B-Device
simulators	I-Device
permit	O
the	O
study	O
of	O
a	O
quantum	O
system	O
in	O
a	O
programmable	O
fashion	O
.	O
</s>
<s>
Quantum	B-Device
simulators	I-Device
may	O
be	O
contrasted	O
with	O
generally	O
programmable	O
"	O
digital	O
"	O
quantum	B-Architecture
computers	I-Architecture
,	O
which	O
would	O
be	O
capable	O
of	O
solving	O
a	O
wider	O
class	O
of	O
quantum	O
problems	O
.	O
</s>
<s>
A	O
universal	B-Device
quantum	I-Device
simulator	I-Device
is	O
a	O
quantum	B-Architecture
computer	I-Architecture
proposed	O
by	O
Yuri	O
Manin	O
in	O
1980	O
and	O
Richard	O
Feynman	O
in	O
1982	O
.	O
</s>
<s>
Feynman	O
showed	O
that	O
a	O
classical	O
Turing	B-Architecture
machine	I-Architecture
would	O
not	O
be	O
able	O
to	O
simulate	O
a	O
quantum	O
effect	O
,	O
while	O
his	O
hypothetical	O
universal	O
quantum	B-Architecture
computer	I-Architecture
would	O
be	O
able	O
to	O
mimic	O
needed	O
quantum	O
effect	O
.	O
</s>
<s>
A	O
quantum	O
system	O
of	O
many	O
particles	O
could	O
be	O
simulated	O
by	O
a	O
quantum	B-Architecture
computer	I-Architecture
using	O
a	O
number	O
of	O
quantum	O
bits	O
similar	O
to	O
the	O
number	O
of	O
particles	O
in	O
the	O
original	O
system	O
.	O
</s>
<s>
Quantum	B-Device
simulators	I-Device
have	O
been	O
realized	O
on	O
a	O
number	O
of	O
experimental	O
platforms	O
,	O
including	O
systems	O
of	O
ultracold	O
quantum	O
gases	O
,	O
polar	O
molecules	O
,	O
trapped	O
ions	O
,	O
photonic	O
systems	O
,	O
quantum	O
dots	O
,	O
and	O
superconducting	O
circuits	O
.	O
</s>
<s>
Many	O
important	O
problems	O
in	O
physics	O
,	O
especially	O
low-temperature	O
physics	O
and	O
many-body	B-Algorithm
physics	I-Algorithm
,	O
remain	O
poorly	O
understood	O
because	O
the	O
underlying	O
quantum	O
mechanics	O
is	O
vastly	O
complex	O
.	O
</s>
<s>
Quantum	B-Device
simulators	I-Device
provide	O
an	O
alternative	O
route	O
to	O
understanding	O
the	O
properties	O
of	O
these	O
systems	O
.	O
</s>
<s>
Quantum	B-Device
simulators	I-Device
can	O
solve	O
problems	O
which	O
are	O
difficult	O
to	O
simulate	O
on	O
classical	O
computers	O
because	O
they	O
directly	O
exploit	O
quantum	O
properties	O
of	O
real	O
particles	O
.	O
</s>
<s>
Recently	O
quantum	B-Device
simulators	I-Device
have	O
been	O
used	O
to	O
obtain	O
time	O
crystals	O
and	O
quantum	O
spin	O
liquids	O
.	O
</s>
<s>
and	O
Islam	O
et	O
al.	O
,	O
used	O
adiabatic	O
quantum	B-Device
simulation	I-Device
to	O
demonstrate	O
the	O
sharpening	O
of	O
a	O
phase	O
transition	O
between	O
paramagnetic	O
and	O
ferromagnetic	O
ordering	O
as	O
the	O
number	O
of	O
spins	O
increased	O
from	O
2	O
to	O
9	O
.	O
</s>
<s>
demonstrated	O
digital	O
quantum	B-Device
simulation	I-Device
with	O
up	O
to	O
6	O
ions	O
.	O
</s>
<s>
Islam	O
,	O
et	O
al.	O
,	O
demonstrated	O
adiabatic	O
quantum	B-Device
simulation	I-Device
of	O
the	O
transverse	O
Ising	O
model	O
with	O
variable	O
(	O
long	O
)	O
range	O
interactions	O
with	O
up	O
to	O
18	O
trapped	O
ion	O
spins	O
,	O
showing	O
control	O
of	O
the	O
level	O
of	O
spin	O
frustration	O
by	O
adjusting	O
the	O
antiferromagnetic	O
interaction	O
range	O
.	O
</s>
<s>
Many	O
ultracold	O
atom	O
experiments	O
are	O
examples	O
of	O
quantum	B-Device
simulators	I-Device
.	O
</s>
<s>
These	O
include	O
experiments	O
studying	O
bosons	B-Algorithm
or	O
fermions	B-Algorithm
in	O
optical	O
lattices	O
,	O
the	O
unitary	O
Fermi	O
gas	O
,	O
Rydberg	O
atom	O
arrays	O
in	O
optical	O
tweezers	O
.	O
</s>
<s>
A	O
common	O
thread	O
for	O
these	O
experiments	O
is	O
the	O
capability	O
of	O
realizing	O
generic	O
Hamiltonians	O
,	O
such	O
as	O
the	O
Hubbard	B-Algorithm
or	O
transverse-field	O
Ising	O
Hamiltonian	O
.	O
</s>
<s>
Quantum	B-Device
simulators	I-Device
using	O
superconducting	O
qubits	O
fall	O
into	O
two	O
main	O
categories	O
.	O
</s>
<s>
First	O
,	O
so	O
called	O
quantum	B-Algorithm
annealers	I-Algorithm
determine	O
ground	O
states	O
of	O
certain	O
Hamiltonians	O
after	O
an	O
adiabatic	O
ramp	O
.	O
</s>
<s>
This	O
approach	O
is	O
sometimes	O
called	O
adiabatic	O
quantum	B-Architecture
computing	I-Architecture
.	O
</s>
<s>
Several	O
important	O
recent	O
results	O
include	O
the	O
realization	O
of	O
a	O
Mott	O
insulator	O
in	O
a	O
driven-dissipative	O
Bose-Hubbard	B-Algorithm
system	I-Algorithm
and	O
studies	O
of	O
phase	O
transitions	O
in	O
lattices	O
of	O
superconducting	O
resonators	O
coupled	O
to	O
qubits	O
.	O
</s>
