A breakthrough finding that was made as a result of a fortunate accident in
the lab has important ramifications for the development of quantum computers
and sensors in addition to solving an issue that has persisted for more than
50 years.A team of engineers from UNSW Sydney has achieved what a renowned
scientist initially said was achievable in 1961 but has evaded everyone
since: manipulating the nucleus of a single atom using just electric fields.
Their findings were published today in Nature.
"This discovery means that we now have a pathway to build quantum computers
using single-atom spins without the need for any oscillating magnetic field
for their operation," explains Andrea Morello, Scientia Professor of Quantum
Engineering at UNSW. Additionally, we may employ these nuclei to find
answers to basic quantum scientific puzzles or as incredibly accurate
sensors of electric and magnetic forces.
The fact that an electric field may be used to regulate a nuclear spin
rather than a magnetic field has significant ramifications. The rules of
physics state that it is difficult to limit magnetic fields to extremely
tiny regions since they tend to have a wide area of impact. This
necessitates the use of big coils and high currents to generate magnetic
fields. On the other hand, small electrode tips may create electric fields,
and those fields drop off extremely abruptly from there. This will greatly
simplify the control of individual atoms used in nanoelectronic
devices.
brand-new paradigm
The technology of nuclear magnetic resonance, which is extensively employed
in industries as diverse as mining, chemistry, and medicine, is being shaken
up by the finding, according to Prof. Morello. He claims that one of the
most widely used techniques in contemporary physics, chemistry, and even
medicine or mining is nuclear magnetic resonance. "Mining corporations
employ it to analyze rock samples, while doctors use it to view the inside
of a patient's body in exquisite detail. The use of magnetic fields to
regulate and detect the nuclei might be a drawback for some applications,
despite how well everything works.
In order to clarify the distinction between manipulating nuclear spins with
magnetic and electric fields, Prof. Morello compares it to a pool
table.
He compares it to trying to move a certain ball on a pool table by raising
and shaking the entire table when doing magnetic resonance. The targeted
ball will be moved, but we'll also move every other ball as well.
The invention of electric resonance is comparable to receiving a real pool
stick to strike the ball precisely where you want it, according to one
person.
Nicolaas Bloembergen, a magnetic resonance pioneer and Nobel Laureate,
initially proposed using electric fields to regulate nuclear spins in 1961.
Amazingly, Prof. Morello was absolutely ignorant that his team had solved
this long-standing challenge.
Despite spending the last 20 years of my life working on spin resonance,
Prof. Morello admits that he has never heard of nuclear electric resonance.
"This phenomenon was'rediscovered' by total accident; I would never have
thought to seek for it. Since the initial attempts to show it proved to be
too difficult, the entire topic of nuclear electric resonance has
essentially been inactive for more than 50 years.
I was just curious.
The goal of the initial experiment was to perform nuclear magnetic
resonance on a single antimony atom because this element has a significant
nuclear spin. Dr. Serwan Asaad, one of the study's primary authors,
explains: "Our first objective was to research the border between the
quantum world and the classical world, which is determined by the nuclear
spin's chaotic behavior. Without any practical use in mind, this was just a
project done out of curiosity.
But as soon as we got going on the experiment, we realized something wasn't
right. According to Dr. Vincent Mourik, another main author on the article,
"The nucleus behaved quite oddly, refusing to respond at certain frequencies
while exhibiting a significant response at others.
We were perplexed by this for a time before realizing that we were doing
electric resonance rather than magnetic resonance in a "eureka
moment."
In order to regulate the antimony atom's nucleus, we constructed a device
with an antimony atom and a specific antenna that was designed to produce a
high-frequency magnetic field. We put a lot of power into the antenna and
blew it up since our experiment needs a very strong magnetic field.
Play now
Normally, when you blow up the antenna with tiny nuclei like phosphorous,
it's "game over" and you have to throw the equipment away, claims Dr.
Mourik."However, the experiment continued to function with the antimony
nucleus. It turns out that the antenna was producing a significant electric
field after the damage rather than a magnetic field. Therefore, nuclear
electric resonance was "rediscovered."
The researchers employed advanced computer modeling to determine precisely
how the electric field affects the spin of the nucleus after establishing
their ability to regulate the nucleus with electric fields. Through the
distortion of the atomic bonds around the nucleus caused by the electric
field, nuclear electric resonance was shown to be a really local, tiny
phenomena.
According to Prof. Morello, "This groundbreaking result will open up a
treasure trove of discoveries and applications." "The system we built has
enough complexity to explore how the quantum world gives rise to the
everyday classical world that humans perceive. Additionally, we may leverage
its quantum complexity to create electromagnetic field sensors with far
higher sensitivity. All of this is included in a straightforward
silicon-based electrical device that can be operated by applying very modest
voltages to a metal electrode.
