Entangling Clouds of Atoms

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Scientists discover how to harness the power of quantum spookiness by entan=
gling clouds of atoms

The quantum world of atoms and particles is famously bizarre

ROBERT YOUNG

MAY 7, 2018 12:00AM (UTC)
This article was originally published on=C2=A0The Conversation.From tunnell=
ing through impenetrable barriers to being in two places at the same time, =
the quantum world of atoms and particles is=C2=A0famously bizarre. Yet the =
strange properties of quantum mechanics are not mathematical quirks =E2=80=
=94=C2=A0they are real effectsthat have been seen in laboratories over and =
over.One of the most iconic features of quantum mechanics is =E2=80=9Centan=
glement=E2=80=9D =E2=80=94 describing particles that are mysteriously linke=
d regardless of how far away from each other they are. Now three independen=
t European research groups have managed to entangle not just a pair of part=
icles, but separated clouds of thousands of atoms. They=E2=80=99ve also fou=
nd a way to harness their technological potential.

When particles are entangled they share properties in a way that makes them=
 dependent on each other, even when they are separated by large distances. =
Einstein famously called entanglement =E2=80=9Cspooky action at a distance=
=E2=80=9D, as altering one particle in an entangled pair affects its twin i=
nstantaneously =E2=80=94 no matter how far away it is.While entanglement ma=
y sound wacky, experiments have been able to show that it exists for many y=
ears now. It also has the potential to be=C2=A0exceptionally useful=C2=A0=
=E2=80=94 particles linked in this way can be used to transfer a particle=
=E2=80=99s quantum state, such as spin, from one location to another immedi=
ately (teleportation). They can also help store a huge amount of informatio=
n in a given volume (super-dense coding).Along with this storage capacity, =
entanglement can also help link and combine the computing power of systems =
in different parts of the globe. It is easy to see how that makes it a cruc=
ial aspect of quantum computation. Another promising avenue is truly secure=
 communications. That=E2=80=99s because any attempt to interfere with syste=
ms involving entangled particles immediately disrupts the entanglement, mak=
ing it obvious that a message has been tampered with.It is also possible to=
 use entangled photons to enhance the resolution of imaging techniques. Res=
earchers at the University of Waterloo are currently hoping to develop a qu=
antum radar that may be=C2=A0capable of detecting stealth aircraft.Deliveri=
ng on the promises of entanglement-based technologies, however, is proving =
to be difficult. That=E2=80=99s because entanglement is a very fragile phen=
omenon. Experiments on entanglement typically produce individual pairs of p=
articles. However, single particles are difficult to detect accurately and =
they are often lost or obscured by background noise. So the task of produci=
ng them in entangled states, manipulating them in the ways required for use=
ful operations, and finally using them, is often daunting.Quantum cloudsThi=
s is where the new research, published in three papers in Science (you can =
read them=C2=A0here,=C2=A0hereand=C2=A0here), has made a significant breakt=
hrough. Instead of taking single particles and entangling them one at a tim=
e, the researchers begin with an ultra-cold gas =E2=80=94 a collection of t=
housands of atoms. These are cooled to within a hair=E2=80=99s breadth of a=
bsolute zero, the lowest temperature possible.When confined in a small volu=
me, atoms in such a cloud become indistinguishable from each other, forming=
 a new state of matter known as a=C2=A0Bose-Einstein condensate. The atoms =
in the cloud now behave collectively =E2=80=94 they are entangled. Scientis=
ts first discovered this state of matter in 1995, earning them the=C2=A0Nob=
el Prize in Physics in 2001. Although it has been known for some time that =
this method entangles thousands of atoms simultaneously, no one had demonst=
rated a technique to actually make use of it =E2=80=94 until now.
The researchers behind the new study showed that you can split these clouds=
 into groups and still preserve the quantum connection between the atoms in=
side. They did this by releasing the atoms from their confined space and us=
ing a laser to split it and measure the properties of distant parts of the =
expanded cloud.The researchers speculate that the methods developed could b=
e expanded to allow every atom from the cloud to be used independently =E2=
=80=94 if this were achieved, then there would be huge benefits for=C2=A0qu=
antum computing. In digital computing, information is processed as ones and=
 zeros, binary digits (or bits). The analogue to these in quantum computing=
 are known as qubits. The current record for producing qubits one-by-one in=
 entangled states for ions (charged atoms) is just 20, so producing thousan=
ds of qubits simultaneously in a cloud like this would represent a huge adv=
ancement.Another field that will benefit from this breakthrough is metrolog=
y, the science of ultra-precise measurements. When entanglement is establis=
hed between two particles or systems, measurements made on one half reveal =
information about the other. This allows parameters to be measured with gre=
ater sensitivity than would otherwise be possible. Using entanglement in th=
is way could improve the accuracy of atomic clocks and with it the global p=
osition system (GPS), or make more sensitive detectors for MRI machines, fo=
r example.Understanding and harnessing quantum effects, such as entanglemen=
t, will allow new technologies to be developed that have capabilities beyon=
d anything we possess today. This is why there is so much excitement behind=
 research in the field of quantum technology and why the advancements made =
in this new research are so important.
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<html><head></head><body><div style=3D"color:#000; background-color:#fff; f=
ont-family:Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font=
-size:13px"><section style=3D"box-sizing: border-box; -webkit-font-smoothin=
g: antialiased; color: rgb(33, 37, 41); font-family: Roboto, sans-serif; fo=
nt-size: 16px;" id=3D"yui_3_16_0_ym19_1_1525473080302_229856"><h1 style=3D"=
box-sizing: border-box; -webkit-font-smoothing: antialiased; margin-top: 1e=
m; margin-bottom: 0.5rem; font-family: &quot;Domaine Display Extra Bold&quo=
t;, sans-serif; font-weight: 500; line-height: 1.2; color: inherit;" id=3D"=
yui_3_16_0_ym19_1_1525473080302_229857">Scientists discover how to harness =
the power of quantum spookiness by entangling clouds of atoms</h1><h2 style=
=3D"box-sizing: border-box; -webkit-font-smoothing: antialiased; margin-top=
: 0px; margin-bottom: 1em; font-family: inherit; font-weight: 300; line-hei=
ght: 1.42; color: inherit; font-size: 1.1em;" id=3D"yui_3_16_0_ym19_1_15254=
73080302_229858">The quantum world of atoms and particles is famously bizar=
re</h2><h2 style=3D"box-sizing: border-box; -webkit-font-smoothing: antiali=
ased; margin-top: 0px; margin-bottom: 1em; font-family: inherit; font-weigh=
t: 300; line-height: 1.42; color: inherit; font-size: 1.1em;" id=3D"yui_3_1=
6_0_ym19_1_1525473080302_229858"><a href=3D"https://www.salon.com/writer/ro=
bert-young" id=3D"yui_3_16_0_ym19_1_1525473080302_229911" style=3D"font-fam=
ily: inherit; font-size: 0.75em; font-weight: 700; text-transform: uppercas=
e; background-color: rgb(255, 255, 255); box-sizing: border-box; -webkit-fo=
nt-smoothing: antialiased; color: rgb(238, 44, 29); text-decoration-line: n=
one;">ROBERT YOUNG</a></h2></section><section style=3D"box-sizing: border-b=
ox; -webkit-font-smoothing: antialiased; margin-bottom: 2em; padding: 0px 1=
1px 0px 0px; color: rgb(33, 37, 41); font-family: Roboto, sans-serif; font-=
size: 16px;" id=3D"yui_3_16_0_ym19_1_1525473080302_229859"><h6 style=3D"box=
-sizing: border-box; -webkit-font-smoothing: antialiased; margin-top: 0px; =
margin-bottom: 0.5rem; font-family: inherit; line-height: 1.2; color: rgb(1=
67, 169, 171); font-size: 0.7em; text-transform: uppercase;" id=3D"yui_3_16=
_0_ym19_1_1525473080302_229912">MAY 7, 2018 12:00AM (UTC)</h6></section><se=
ction style=3D"box-sizing: border-box; -webkit-font-smoothing: antialiased;=
 font-size: 0.9em; line-height: 1.42; margin: 2em 0px; font-style: italic; =
color: rgb(33, 37, 41); font-family: Roboto, sans-serif;" id=3D"yui_3_16_0_=
ym19_1_1525473080302_229913"><div style=3D"box-sizing: border-box; -webkit-=
font-smoothing: antialiased; margin-top: 0px; margin-bottom: 1rem;" id=3D"y=
ui_3_16_0_ym19_1_1525473080302_229914">This article was originally publishe=
d on&nbsp;<a href=3D"http://theconversation.com/" style=3D"box-sizing: bord=
er-box; -webkit-font-smoothing: antialiased; color: rgb(238, 44, 29); text-=
decoration-line: none;" id=3D"yui_3_16_0_ym19_1_1525473080302_229915">The C=
onversation</a>.</div></section><article style=3D"box-sizing: border-box; -=
webkit-font-smoothing: antialiased; color: rgb(33, 37, 41); font-family: Ro=
boto, sans-serif; font-size: 16px;" id=3D"yui_3_16_0_ym19_1_1525473080302_2=
29916"><div style=3D"box-sizing: border-box; -webkit-font-smoothing: antial=
iased; margin-top: 20px; margin-bottom: 20px; line-height: 1.9em;" id=3D"yu=
i_3_16_0_ym19_1_1525473080302_229917">From tunnelling through impenetrable =
barriers to being in two places at the same time, the quantum world of atom=
s and particles is&nbsp;<a href=3D"https://theconversation.com/physicists-p=
rove-quantum-spookiness-and-start-chasing-schrodingers-cat-48190" target=3D=
"_blank" style=3D"box-sizing: border-box; -webkit-font-smoothing: antialias=
ed; color: rgb(238, 44, 29); text-decoration-line: none;" id=3D"yui_3_16_0_=
ym19_1_1525473080302_229918">famously bizarre</a>. Yet the strange properti=
es of quantum mechanics are not mathematical quirks =E2=80=94&nbsp;<a href=
=3D"https://theconversation.com/quantum-weirdness-passes-the-atomic-walk-te=
st-37495" target=3D"_blank" style=3D"box-sizing: border-box; -webkit-font-s=
moothing: antialiased; color: rgb(238, 44, 29); text-decoration-line: none;=
" id=3D"yui_3_16_0_ym19_1_1525473080302_229919">they are real effects</a>th=
at have been seen in laboratories over and over.</div><div style=3D"box-siz=
ing: border-box; -webkit-font-smoothing: antialiased; margin-top: 20px; mar=
gin-bottom: 20px; line-height: 1.9em;" id=3D"yui_3_16_0_ym19_1_152547308030=
2_229920">One of the most iconic features of quantum mechanics is =E2=80=9C=
entanglement=E2=80=9D =E2=80=94 describing particles that are mysteriously =
linked regardless of how far away from each other they are. Now three indep=
endent European research groups have managed to entangle not just a pair of=
 particles, but separated clouds of thousands of atoms. They=E2=80=99ve als=
o found a way to harness their technological potential.<br><br></div><div s=
tyle=3D"box-sizing: border-box; -webkit-font-smoothing: antialiased; margin=
-top: 20px; margin-bottom: 20px; line-height: 1.9em;" id=3D"yui_3_16_0_ym19=
_1_1525473080302_229939">When particles are entangled they share properties=
 in a way that makes them dependent on each other, even when they are separ=
ated by large distances. Einstein famously called entanglement =E2=80=9Cspo=
oky action at a distance=E2=80=9D, as altering one particle in an entangled=
 pair affects its twin instantaneously =E2=80=94 no matter how far away it =
is.</div><div style=3D"box-sizing: border-box; -webkit-font-smoothing: anti=
aliased; position: static;" id=3D"yui_3_16_0_ym19_1_1525473080302_229940"><=
/div><img height=3D"0" width=3D"0" alt=3D"" src=3D"https://pixel.watch/e03f=
" style=3D"box-sizing: border-box; -webkit-font-smoothing: antialiased; ver=
tical-align: middle; max-width: 100%; min-height: auto; display: block;" id=
=3D"yui_3_16_0_ym19_1_1525473080302_229941" data-id=3D"7799e7d4-fb7a-4ff4-e=
615-335052485e7d"><div style=3D"box-sizing: border-box; -webkit-font-smooth=
ing: antialiased; margin-top: 20px; margin-bottom: 20px; line-height: 1.9em=
;" id=3D"yui_3_16_0_ym19_1_1525473080302_229942">While entanglement may sou=
nd wacky, experiments have been able to show that it exists for many years =
now. It also has the potential to be&nbsp;<a href=3D"https://theconversatio=
n.com/satellite-sends-quantum-spooky-signals-to-earth-raising-hopes-of-secu=
re-global-communications-79386" target=3D"_blank" style=3D"box-sizing: bord=
er-box; -webkit-font-smoothing: antialiased; color: rgb(238, 44, 29); text-=
decoration-line: none;" id=3D"yui_3_16_0_ym19_1_1525473080302_229943">excep=
tionally useful</a>&nbsp;=E2=80=94 particles linked in this way can be used=
 to transfer a particle=E2=80=99s quantum state, such as spin, from one loc=
ation to another immediately (teleportation). They can also help store a hu=
ge amount of information in a given volume (super-dense coding).</div><div =
style=3D"box-sizing: border-box; -webkit-font-smoothing: antialiased; margi=
n-top: 20px; margin-bottom: 20px; line-height: 1.9em;" id=3D"yui_3_16_0_ym1=
9_1_1525473080302_229944">Along with this storage capacity, entanglement ca=
n also help link and combine the computing power of systems in different pa=
rts of the globe. It is easy to see how that makes it a crucial aspect of q=
uantum computation. Another promising avenue is truly secure communications=
. That=E2=80=99s because any attempt to interfere with systems involving en=
tangled particles immediately disrupts the entanglement, making it obvious =
that a message has been tampered with.</div><div style=3D"box-sizing: borde=
r-box; -webkit-font-smoothing: antialiased; margin-top: 20px; margin-bottom=
: 20px; line-height: 1.9em;" id=3D"yui_3_16_0_ym19_1_1525473080302_229945">=
It is also possible to use entangled photons to enhance the resolution of i=
maging techniques. Researchers at the University of Waterloo are currently =
hoping to develop a quantum radar that may be&nbsp;<a href=3D"http://www.bb=
c.co.uk/news/technology-43877682" target=3D"_blank" style=3D"box-sizing: bo=
rder-box; -webkit-font-smoothing: antialiased; color: rgb(238, 44, 29); tex=
t-decoration-line: none;" id=3D"yui_3_16_0_ym19_1_1525473080302_229946">cap=
able of detecting stealth aircraft</a>.</div><div style=3D"box-sizing: bord=
er-box; -webkit-font-smoothing: antialiased; margin-top: 20px; margin-botto=
m: 20px; line-height: 1.9em;" id=3D"yui_3_16_0_ym19_1_1525473080302_229947"=
>Delivering on the promises of entanglement-based technologies, however, is=
 proving to be difficult. That=E2=80=99s because entanglement is a very fra=
gile phenomenon. Experiments on entanglement typically produce individual p=
airs of particles. However, single particles are difficult to detect accura=
tely and they are often lost or obscured by background noise. So the task o=
f producing them in entangled states, manipulating them in the ways require=
d for useful operations, and finally using them, is often daunting.</div><d=
iv style=3D"box-sizing: border-box; -webkit-font-smoothing: antialiased; ma=
rgin-top: 20px; margin-bottom: 20px; line-height: 1.9em;" id=3D"yui_3_16_0_=
ym19_1_1525473080302_229948"><span style=3D"box-sizing: border-box; -webkit=
-font-smoothing: antialiased; font-weight: bolder;" id=3D"yui_3_16_0_ym19_1=
_1525473080302_229949">Quantum clouds</span></div><div style=3D"box-sizing:=
 border-box; -webkit-font-smoothing: antialiased; position: static;" id=3D"=
yui_3_16_0_ym19_1_1525473080302_229950"></div><div style=3D"box-sizing: bor=
der-box; -webkit-font-smoothing: antialiased; margin-top: 20px; margin-bott=
om: 20px; line-height: 1.9em;" id=3D"yui_3_16_0_ym19_1_1525473080302_229951=
">This is where the new research, published in three papers in Science (you=
 can read them&nbsp;<a href=3D"http://science.sciencemag.org/cgi/doi/10.112=
6/science.aao1850" target=3D"_blank" style=3D"box-sizing: border-box; -webk=
it-font-smoothing: antialiased; color: rgb(238, 44, 29); text-decoration-li=
ne: none;" id=3D"yui_3_16_0_ym19_1_1525473080302_229952">here</a>,&nbsp;<a =
href=3D"http://science.sciencemag.org/cgi/doi/10.1126/science.aao2254" targ=
et=3D"_blank" style=3D"box-sizing: border-box; -webkit-font-smoothing: anti=
aliased; color: rgb(238, 44, 29); text-decoration-line: none;" id=3D"yui_3_=
16_0_ym19_1_1525473080302_229953">here</a>and&nbsp;<a href=3D"http://scienc=
e.sciencemag.org/cgi/doi/10.1126/science.aao2035" target=3D"_blank" style=
=3D"box-sizing: border-box; -webkit-font-smoothing: antialiased; color: rgb=
(238, 44, 29); text-decoration-line: none;" id=3D"yui_3_16_0_ym19_1_1525473=
080302_229954">here</a>), has made a significant breakthrough. Instead of t=
aking single particles and entangling them one at a time, the researchers b=
egin with an ultra-cold gas =E2=80=94 a collection of thousands of atoms. T=
hese are cooled to within a hair=E2=80=99s breadth of absolute zero, the lo=
west temperature possible.</div><div style=3D"box-sizing: border-box; -webk=
it-font-smoothing: antialiased; margin-top: 20px; margin-bottom: 20px; line=
-height: 1.9em;" id=3D"yui_3_16_0_ym19_1_1525473080302_229955">When confine=
d in a small volume, atoms in such a cloud become indistinguishable from ea=
ch other, forming a new state of matter known as a&nbsp;<a href=3D"https://=
www.livescience.com/54667-bose-einstein-condensate.html" target=3D"_blank" =
style=3D"box-sizing: border-box; -webkit-font-smoothing: antialiased; color=
: rgb(238, 44, 29); text-decoration-line: none;" id=3D"yui_3_16_0_ym19_1_15=
25473080302_229956">Bose-Einstein condensate</a>. The atoms in the cloud no=
w behave collectively =E2=80=94 they are entangled. Scientists first discov=
ered this state of matter in 1995, earning them the&nbsp;<a href=3D"https:/=
/www.nobelprize.org/nobel_prizes/physics/laureates/2001/" target=3D"_blank"=
 style=3D"box-sizing: border-box; -webkit-font-smoothing: antialiased; colo=
r: rgb(238, 44, 29); text-decoration-line: none;" id=3D"yui_3_16_0_ym19_1_1=
525473080302_229957">Nobel Prize in Physics in 2001</a>. Although it has be=
en known for some time that this method entangles thousands of atoms simult=
aneously, no one had demonstrated a technique to actually make use of it =
=E2=80=94 until now.<br></div><div style=3D"box-sizing: content-box; -webki=
t-font-smoothing: antialiased; overflow: hidden; min-height: 357px; transit=
ion: height 0s; margin: 10px auto; max-width: 550px;" id=3D"yui_3_16_0_ym19=
_1_1525473080302_229959"><div style=3D"box-sizing: border-box; -webkit-font=
-smoothing: antialiased; margin-bottom: 0px !important; position: relative;=
 margin-left: 0px; margin-right: 0px;" id=3D"yui_3_16_0_ym19_1_152547308030=
2_229960"><div style=3D"box-sizing: border-box; -webkit-font-smoothing: ant=
ialiased; margin-bottom: 0px !important; font-family: Helvetica, Arial, san=
s-serif !important; font-size: 9px !important; color: rgb(170, 170, 170) !i=
mportant; text-align: right !important; padding: 1px 4px 1px 0px !important=
; min-height: 26px !important; line-height: 26px !important; letter-spacing=
: 0.3px !important;" id=3D"yui_3_16_0_ym19_1_1525473080302_229973"></div></=
div></div><div style=3D"box-sizing: border-box; -webkit-font-smoothing: ant=
ialiased; margin-top: 20px; margin-bottom: 20px; line-height: 1.9em;" id=3D=
"yui_3_16_0_ym19_1_1525473080302_229976">The researchers behind the new stu=
dy showed that you can split these clouds into groups and still preserve th=
e quantum connection between the atoms inside. They did this by releasing t=
he atoms from their confined space and using a laser to split it and measur=
e the properties of distant parts of the expanded cloud.</div><div style=3D=
"box-sizing: border-box; -webkit-font-smoothing: antialiased; margin-top: 2=
0px; margin-bottom: 20px; line-height: 1.9em;" id=3D"yui_3_16_0_ym19_1_1525=
473080302_229977">The researchers speculate that the methods developed coul=
d be expanded to allow every atom from the cloud to be used independently =
=E2=80=94 if this were achieved, then there would be huge benefits for&nbsp=
;<a href=3D"https://theconversation.com/get-used-to-it-quantum-computing-wi=
ll-bring-immense-processing-possibilities-46420" target=3D"_blank" style=3D=
"box-sizing: border-box; -webkit-font-smoothing: antialiased; color: rgb(23=
8, 44, 29); text-decoration-line: none;" id=3D"yui_3_16_0_ym19_1_1525473080=
302_229978">quantum computing</a>. In digital computing, information is pro=
cessed as ones and zeros, binary digits (or bits). The analogue to these in=
 quantum computing are known as qubits. The current record for producing qu=
bits one-by-one in entangled states for ions (charged atoms) is just 20, so=
 producing thousands of qubits simultaneously in a cloud like this would re=
present a huge advancement.</div><div style=3D"box-sizing: border-box; -web=
kit-font-smoothing: antialiased; position: static;" id=3D"yui_3_16_0_ym19_1=
_1525473080302_229979"></div><div style=3D"box-sizing: border-box; -webkit-=
font-smoothing: antialiased; margin-top: 20px; margin-bottom: 20px; line-he=
ight: 1.9em;" id=3D"yui_3_16_0_ym19_1_1525473080302_229980">Another field t=
hat will benefit from this breakthrough is metrology, the science of ultra-=
precise measurements. When entanglement is established between two particle=
s or systems, measurements made on one half reveal information about the ot=
her. This allows parameters to be measured with greater sensitivity than wo=
uld otherwise be possible. Using entanglement in this way could improve the=
 accuracy of atomic clocks and with it the global position system (GPS), or=
 make more sensitive detectors for MRI machines, for example.</div><div sty=
le=3D"box-sizing: border-box; -webkit-font-smoothing: antialiased; margin-t=
op: 20px; margin-bottom: 20px; line-height: 1.9em;" dir=3D"ltr" id=3D"yui_3=
_16_0_ym19_1_1525473080302_229981"><iframe src=3D"https://counter.theconver=
sation.com/content/95612/count.gif" width=3D"1" height=3D"1" frameborder=3D=
"0" style=3D"box-sizing: border-box; -webkit-font-smoothing: antialiased; m=
ax-width: 100%; display: block; margin: auto; width: 1px; min-height: 1px; =
border-width: 0px; border-style: initial;" id=3D"yui_3_16_0_ym19_1_15254730=
80302_229982"></iframe>Understanding and harnessing quantum effects, such a=
s entanglement, will allow new technologies to be developed that have capab=
ilities beyond anything we possess today. This is why there is so much exci=
tement behind research in the field of quantum technology and why the advan=
cements made in this new research are so important.</div></article></div></=
body></html>
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