New 'invisibility cloak' type designed

objects more obvious, not less, the

researchers found

A new "broadband" invisibility cloak

which hides objects over a wide range
of frequencies has been devised.

Ma
ny "invisibility" techniques actually make

Despite the hype about Harry Potter-style cloaks, our best current designs can only conceal
objects at specific wavelengths of light or microwaves.

At other frequencies, invisibility cloaks actually make things more visible, not less,US
physicists found.

Their solution is a new ultrathin, electronic system, which they describe in Physical Review
Letters.

If you want to make an object transparent at all angles and over broad bandwidths,
this is a good solutionAndrea Alu, University of Texas

"Our active cloak is a completely new concept and design, aimed at beating the limits of
[current cloaks] and we show that it indeed does," said Prof Andrea Alu, from the University of
Texas at Austin.

"If you want to make an object transparent at all angles and over broad bandwidths, this is a
good solution.

"We are looking into realising this technology at the moment, but we are still at the early
stages."

Passive vs Active

While the popular image of an invisibility cloak is the magical robe worn by Harry Potter, there
is another kind which is not so far-fetched.

The first working model - which concealed a small copper cylinder by bending microwaves
around it - was first demonstrated in 2006.

The sphere on the right is "cloaked" but actually

scatters more radiation than when bare (left)

It was built with a thin shell of metamaterials - artificial composites whose structures allow
properties which do not exist in nature.

Cloaking materials could have applications in the military, microscopy, biomedical sensing, and
energy harvesting devices.

The trouble with current designs is they only work at limited bandwidths. Even this"perfect"
3D cloak demonstrated last year could only hide objects from microwaves.
At other frequencies the cloak acts as a beacon - making the hidden object more obvious - as
Prof Alu and his team have now demonstrated in a new study in Physical Review X.

They looked at three popular types of "passive" cloaks - which do not require electricity - a
plasmonic cloak, a mantle cloak, and a transformation-optics cloak.

Other ways to disappear

 Optical camouflage technology: A modified background image is projected onto a

cloak of retro-reflective material (the kind used to make projector screens); the wearer
becomes invisible to anyone standing at the projection source

 The "mirage effect": Electric current is passed through submerged carbon nanotubes
to create very high local temperatures, this causes light to bounce off them, hiding
objects behind

 Adaptive heat cloaking: A camera records background temperatures, these are

displayed by sheets of hexagonal pixels which change temperature very quickly,
camouflaging even moving vehicles from heat-sensitive cameras

 Calcite crystal prism: Calcite crystals send the two polarisations of light in different
directions. By gluing prism-shaped crystals together in a specific geometry, polarised
light can be directed around small objects, effectively cloaking them

All three types scattered more waves than the bare object they were trying to hide - when
tested over the whole range of the electromagnetic spectrum.

"If you suppress scattering in one range, you need to pay the price, with interest, in some other
range," Prof Alu told BBC News.

"For example, you might make a cloak that makes an object invisible to red light. But if you
were illuminated by white light (containing all colours) you would actually look bright blue, and
therefore stand out more."

A cloak that allows complete invisibility is "impossible" with current passive designs, the study
concluded.

"When you add material around an object to cloak it, you can't avoid the fact that you are
adding matter, and that this matter still responds to electromagnetic waves," Prof Alu
explained.

Instead, he said, a much more promising avenue is "active" cloaking technology - designs
which rely on electrical power to make objects "vanish".

Active cloaks can be thinner and less conspicuous than passive cloaks.

Alu's team have proposed a new design which uses amplifiers to coat the surface of the object
in an electric current.

This ultrathin cloak would hide an object from detection at a frequency range "orders of
magnitude broader" than any available passive cloaking technology, they wrote.

Nothing's perfect
Prof David Smith of Duke University, one of the team who created the first cloak in 2006, said
the new design was one of the most detailed he had yet seen.

This does not necessarily preclude the Harry Potter cloakProfessor David Smith,
Duke University

"It's an interesting implementation but as presented is probably a bit limited to certain types of
objects," he told BBC News.

"There are limitations even on active materials. It will be interesting to see if it can be
experimentally realised."

Prof Smith points out that even an "imperfect" invisibility cloak might be perfectly sufficient to
build useful devices with real-world applications.

For example, a radio-frequency cloak could improve wireless communications - by helping

them bypass obstacles and reducing interference from neighbouring antennas.

"To most people, making an object 'invisible' means making it transparent to visible
wavelengths. And the visible spectrum is a tiny, tiny sliver of the overall electromagnetic
spectrum," he told BBC News.

"So, this finding does not necessarily preclude the Harry Potter cloak, nor does it preclude any
other narrow bandwidth application of cloaking."

23rd September 2013

The invisibility cloak: Science fact or fiction?
Invisibility cloaks were once firmly rooted in the world of fantasy and fiction. They’ve featured
in countless books, films and television shows from Star Trek to Harry Potter – but could these
works of science fiction ever become science fact? Writer and futurist Arthur C. Clarke certainly
believed so. ‘Any sufficiently advanced technology,’ he declared, ‘is indistinguishable from
magic.’ And he should know – in the 1940s, he correctly predicted the importance of satellites,
which have since become vital for modern communication networks. Who’s to say J.K. Rowling
won’t be lauded for her scientific foresight in fifty years?

Metamaterials

In 2006, Imperial College London Professor, Sir John Pendry, wrote a paper that caught the
imagination of scientists and the public alike. Published in Science magazine, it explored the
use of metamaterials – artificial materials with properties that cannot be found in nature –
which are defined by their internal structure on a microscopic scale, rather than by their
chemical properties. Metamaterials, Pendry proposed, can be used to guide light around
objects, creating the illusion that they’ve disappeared.

Metamaterials are characterised by being ‘reverse refractive’

Pendry’s ‘invisibility cloak’ theory seems extremely promising – in practice, however, things
become a little more complicated. The thickness of the ‘cloak’, or metamaterial, can only be
fractionally larger than visible light’s wavelength, 400-700 nanometers; the thicker the cloak,
the larger the wavelengths blocked. Current cloaks are capable of blocking microwaves, radio
waves and even infrared but are too large to block visible light. Though this may come as a
disappointment to fans keen on emulating their favourite teenage wizard, it has interesting
implications for other industries; cloaking could be used to hide vehicles from infrared
detectors or to protect humans and equipment from radiation.

Reverse refractive

David Montgomery, Research Supervisor at Sharp Laboratories, explains the process to us:
“Metamaterials are currently a very exciting research area for many optical physicists. They
are characterised by being ‘reverse refractive’ – light normally absorbed by a material is
propagated in a metamaterial. The use of this in certain configurations allows perfect image
reproduction by light bending and hence invisibility. It also in principle allows perfect lenses,
that can make photographs with infinitely fine detail – binoculars with the resolution of the
largest telescope and microscopes that can see atoms. Such effects have already been
demonstrated at microwave wavelengths.”

It is only a matter of time before optical devices of this sort will become
commonplace

The potential market for metamaterial cloaking is huge and it’s only one of the ways scientists
have proposed real-life invisibility.

Adaptive heat cloaking

British defence company BAE Systems has developed a technique that they call Adaptive Heat
Cloaking: armoured hexagonal panels heat up or cool down to match surrounding
temperatures, making tanks and equipment invisible to infrared equipment. Optical
camouflage (also known as active camouflage) disguises the wearer by matching the colours
around it, in the same way that a chameleon mimics its surroundings.

Though this technique is in its infancy, it’s already produced some exciting results; images of a
background can be displayed on a special suit, which works like a flexible television screen.
Researchers have even used mirages to cloak objects. Rapidly heated carbon nanotubes reflect
light in a similar way to hot sand or tarmac, creating an illusion of a puddle of water when
we’re really just looking at a reflected image of the sky.

Montgomery says, “It is only a matter of time before optical devices of this sort will become
commonplace.” If his prediction is correct, then we might not have long to wait before the first
light-bending devices hit the market- and if they function as advertised, you won’t see them
coming.

3D Printing: Manufacturing the future

3D-printed colour-flavored sugar.

Avi Reichental has been a key player in the

burgeoning field of 3D printing and is a man
who firmly believes the process is going to
have a serious and positive impact on our
lives.

Digital fabrication

In the insightful TED talk below he states: “[It] is not that 3D printing is going to catapult us
into the future, but rather that it’s actually going to connect us with our heritage, and it’s going
to usher in a new era of localized, distributed manufacturing that is actually based on digital
fabrication.”

He continues, “Think about useful things. You all know your shoe size. How many of you know
the size of the bridge of your nose or the distance between your temples? Anybody? Wouldn’t it
be awesome if you could, for the first time, get eyewear that actually fits you perfectly and
doesn’t require any hinge assembly, so chances are, the hinges are not going to break? But the
implications of 3D printing go well beyond the tips of our noses.”

He illustrates this with the creation of a personalised exoskeleton made by his company 3D
Systems that is helping Amanda Boxtel, who is paralysed from the waist down, to walk again.

Reclaiming symmetry

Reichental says, “The incredible part about what I learned from Amanda is a lot of us are
looking at 3D printing and we say to ourselves, it’s going to replace traditional methods.
Amanda looked at it and she said, it’s an opportunity for me to reclaim my symmetry and to
embrace my authenticity. And you know what? She’s not standing still. She now wants to walk
in high heels.”

It also seems that the possibilities for 3D

printing are limitless and can have an
impact on our lives in an infinite variety of
ways. Take food for example.

Reichental says, “What if we could, for the

first time, make incredible delectables that
are edible?…And what if we could begin to
put ingredients and colours and flavours in
every taste, which means not only delicious
foods but the promise of personalized
nutrition around the corner?”

Complexity is free

The crux of what makes 3D printing so useful and adaptable is that, in Reichental’s own words,
‘complexity is free’.

He says, “The printer doesn’t care if it makes the most rudimentary shape or the most complex
shape, and that is completely turning design and manufacturing on its head as we know it.
Many people think that 3D printing will be the end of manufacturing as we know it. I think that
it’s the opportunity to put tomorrow’s technology in the hands of youngsters that will create
endless abundance of job opportunities, and with that, everybody can become an expert maker
and an expert manufacturer.”

Robots you can wear: Fashion cybernetics -- By Stephen Ebert

Man has developed an obsession with robots. Written about in Homer’s Iliad and even designed by
Leonardo Da Vinci, the idea of building machines to take on our mundane every-day chores has dogged
inventors for centuries. Androids such as Asimo and Topio are marking mankind’s first successes in
creating intelligent robotic companions. We may not be alone much longer.

But far from being the stuff of Steven Spielberg’s pipedreams, scientists are now using cybernetic
technology to improve the quality of human life, even helping the paralysed to walk, as well as paving the
way for a new fusion of fashion and engineering.

While a world where cyborgs and humans mutually exist side-by-side is the talk of pure fantasy, the lines
between them are beginning to blur thanks to the latest robotic innovations giving human arms and legs
robotic-like capability and strength.

The new age of cybernetic fashion

HAL-5 is a robot suit developed by Tokyo-based company Cyberdyne, that toughens and augments
human capabilities. It detects signals via the surface of the skin to understand, and work with natural
human movement. Electrical motors act as artificial muscles to provide assistance to the wearer’s limbs.
 How robot suits help the disabled

A commercial version of HAL is already provided for welfare use,

but it is hoped that HAL-5 can also be used during daily routines.
A full body suit will let factory staff lift heavier items with less
strain, prolonging their working lifespan by preventing injury.

The health benefits could also see HAL provide a breakthrough for
arthritis sufferers. With 10 million serious sufferers in the United
Kingdom HAL could provide life changing benefits for a large
Robot suits, or exoskeletons are
proportion of the population.
more than science fiction
Such systems could also be used by the elderly, who want to fantasies come true. They
continue living independently, helping them to walk up flights of currently perform a very valuable
stairs with minimal effort. However, with prices sitting at the function in helping paraplegics to
£12,000 mark, it could be a while before the engineering is put walk. Berekely Bionics eLegs
into practice. exoskeleton system is one of
these devices.
Time to lighten that load
Stephanie Sablan was left
Cyberdyne isn’t the only company in the race to make its robo- paralysed in a car accident. Using
wear a part of everyday life. Carmaker Honda, who created robot an eLegs exoskeleton she is able
Asimo, have created a Walking Assist Devicedesigned to lighten to walk using it as part of an
the burden of workers stuck on their feet for long periods and for extensive rehabilitation. While
those with weakened leg muscles that are still able to walk. It unable to walk unassisted, eLegs
works by redistributing bodyweight along its frame, and is able to is encouraging Sablan to at least
respond to a person’s movements. act on some of the physical
movements associated with
Similar technology could also end up within the military. A battery
walking, building strength in the
powered exoskeleton dubbed theHuman Universal Load
process.
Carrier(HULC) will, should it be granted approval, give soldiers
and US Marines extra strength on the battlefield. “It’s [eLegs] taking the steps for
me, but I have to balance, I have
The amount of equipment a soldier is required to carry can be
to shift my weight, I have to make
excruciating depending on conditions. The HULC exoskeleton lets
sure i’m in the right place before I
soldiers carry up to 200 pounds of weight for for up to 20
take my next step,” Sablan says in
kilometers on a single battery charge across all terrains, reducing
this clip. Even during the early
the risk of injury and fatigue in the process.
stages, eLegs has helped
“It will enable soldiers to do things they cannot do today, while considerably. “I know mentally
helping to protect them from musculoskeletal injuries.” Jim Ni, and emotionally, it has,” she says.
HULC program manager at Lockheed Martin Missiles and Fire “You can only benefit from this
Control says. program.”

The HULC will even let soldiers run up to 10mph for short periods, “She’s a very positive person
using a “burst mode” to further the speed soldiers will be able to that’s not let her disability
move across the battlefield. overcome her willingness to
continue to achieve and move
HULC is of course unlikely to make it into the hands of civilians, on,” Dr. Akshat Shah says of her
however, devices such as HAL, and Honda’s Walking Assist progress.
Device reveal previously unimaginable possibilities for enhancing
the lives of millions. Currently ten such rehabilitation
facilities in the US are testing
While it may be a while yet before the public get suited up with a eLegs in 2011, until the system is
HAL set of bionic legs, there is hope that such technology may released for all in 2012 so that
one day be within reach of those who need it most. As we’ve even more can benefit.
seen, the fruits of innovation should never be underestimated. It
has the potential to change lives, forever.

FROM THE JULY/AUGUST 2014 ISSUE

Will Human Teleportation Ever Be Possible? By Corey S. Powell|Monday, June 16, 2014

As experiments in relocating particles advance, will we be able to say, "Beam me up, Scotty"
one day soon?
 Star Trek-style teleportation isn't as crazy
as it sounds, though it would depend on
intricate quantum information systems, as
developed by physicist Alex Kuzmich.

Paramount/Everett Collection

Lately it seems like the research world has launched into a full-throttle game of “what
superpower would you choose?” For those who desire invisibility, engineers are developing
exotic materials that can bend an object’s light completely out of view. For would-be telepaths,
neurobiologists are working on ways to read one person’s brain wave patterns and transmit
them into another person’s head.

My personal favorite, though, is perhaps the most outrageous fantasy power of all:
teleportation, the ability to arrive without traveling. Imagine being able to dematerialize from
your living room and show up the next moment in Venice or the Amazon rainforest or the rings
of Saturn (wearing an appropriate space suit, of course). The idea is so seductive that it has
been a mainstay of science fiction since the early days of Star Trek and Doctor Who, but it also
seems an affront to common sense.

Alex Kuzmich's quantum information

system.

Gary Meek/Georgia Tech

Fortunately, common sense doesn’t guide the rules of quantum physics, as evidenced by a
brief 1993 paper with a mouthful of a title: “Teleporting an Unknown Quantum State Via Dual
Classical and Einstein-Podolsky-Rosen Channels.” In it, a team led by Charles Bennett of IBM’s
T.J. Watson Research Center demonstrated how to link two particles together a certain way,
and keep them linked even at great distances.

That connection, known as quantum entanglement, has a remarkable power. It enables

someone holding one of the particles to send, instantaneously, a chunk of information — the
“unknown quantum state” in the paper’s title — to someone else holding the other particle.
Because of that weird quantum connection, the information goes from one person to the other
without physically passing between them. It arrives without traveling.

Relocating information from one particle to another may not sound a lot like, “Scotty,
energize,” but at a fundamental level, they are two versions of the same process. Every atom
in Captain Kirk’s body is a set of data (type of atom, location, energy state and so on); the
captain as a whole is just an enormous collection of those data sets. Teleport all the relevant
information to the surface of a planet, and you can re-create Kirk exactly as he was aboard the
ship.

Well … maybe. Teleportation technology has progressed rapidly since 1993, and it is now being
tested in the lab. But as the crew of the Enterprise repeatedly discovered, human teleportation
is hard to do right and easy to do wrong. There may be better, simpler ways to attain that type
of superpower.
 The iRobot Corp. makes the Ava 500, a
robot that lets workers interact while miles
apart.

iRobot

Log on to a Quantum Computer

Even a limited form of teleportation could be a revelation. Physicists are hard at work
developing a quantum computer, a related technology that processes information using
individual atoms or particles instead of transistors. Such a computer could vastly outperform
traditional processors on certain types of calculations: cracking codes and solving complex
equations, for instance.

More exciting, a quantum computer could lead to the first fully realistic simulations of quantum
phenomena. All of biology, chemistry and nanotechnology fundamentally operate at the
quantum level. Being able to understand those processes on their own terms would be a giant
leap.

Teleportation is a key enabling technology for quantum computing because it allows you to
extract the information the computer produces without disturbing the rest of the system. No
teleportation, no results. Last year, a team led by physicist Alex Kuzmich, then at the Georgia
Institute of Technology, demonstrated a practical form of information teleportation by
entangling a computer’s atoms and photons (particles of light) on demand. Once you can do
that, you can take advantage of that quantum connection to beam data out of your quantum
computer and get it exactly where you need it.

And once you can build a quantum computer, the possibilities keep going. Kuzmich and others
envision entire “quantum networks” that would link together multiple computers and provide
high-speed communications between them. If you think that idea sounds vaguely familiar, you
are right; it’s a quantum version of the Internet.

A primary reason to go down this path is security. Working with entangled particles requires
incredible delicacy, but that also makes it incredibly private. If anyone tries to eavesdrop on an
entangled message, the very act of unwanted listening disrupts the whole teleportation
process. Any message sent over a quantum Internet is therefore perfectly secure — or as
perfect as anything known to humanity. Heartbleed bug? No problem.
 NASA plans to explore Mars via virtual
teleportation.

NASA

What About Me?

Yeah, yeah, yeah. If you are anything like me, you want to know about the unlimited form of teleportation,
the kind that beams people from place to place. Let me temper your enthusiasm with two considerations,
one philosophical and one technological.

First, extracting all the information from Captain Kirk’s body (or yours) requires knowing the physical
state of every atom, which would require total disintegration. Each time Kirk steps into the transporter,
then, he is committing suicide and then getting reborn at the other end. Second, the amount of
information required to re-create him is staggering — about 4.5 x 10 42 bits, by one estimate, determined
recently as part of a highly entertaining graduate physics project at the University of Leicester.

Nobody knows how to collect and transmit that much information. And remember how the slightest
disturbance ruins quantum entanglement? The process of reassembling your atoms would inherently
scramble the information. At this point, it’s suicide at one end without rebirth at the other. Kirk might as
well put on a red shirt first.

The teleportation situation becomes much less bleak if you bend the definition a bit, however. As many a
video game player has noticed, the human brain has a remarkable ability to project itself outside the body
and into other objects or virtual spaces. NASA is exploiting that ability with Human Exploration
Telerobotics, a project that lets astronauts “inhabit” robots in locations that are fatal or inaccessible. A
mechanical astronaut will soon be strolling outside the International Space Station. In the near future, you
might be able to experience space exploration vicariously through a Mars rover or mechanical arms
poking at a distant asteroid.

If that’s too much of a cheat for you, how about a DNA fax machine? Biotech guru J. Craig Venter
proposes that if we find microbial life on Mars, we could sequence its genome locally, transmit the
information and rebuild the organism here on Earth. In principle, Venter notes, the process could go the
other way: It would be possible to send human DNA, along with an appropriate incubator, to distant
planets and synthesize people at the other end. Then your clone could start setting up shop on a world
orbiting Alpha Centauri B.

Cloning still doesn’t fulfill the full superpower fantasy of teleportation, I realize. No, what you ideally want
is a complete mind-upload to your distant doppelganger, so that you/he/she can really be there. That
would reduce the teleportation problem from “probably impossible” to “wildly difficult.” That still leaves
the problem of the brain’s enormous information content. But if you accept that information is the only
thing that defines your mind, the task seems feasible. No longer do you need to assemble atoms
meticulously in the right locations; just the facts will do.

Note a fascinating common thread through all these possibilities. Whether you regard yourself as a pile of
atoms, a DNA sequence, a series of sensory inputs or an elaborate computer file, in all of these
interpretations you are nothing but a stack of data. According to the principle of unitarity, quantum
information is never lost. Put them together, and those two statements lead to a staggering corollary: At
the most fundamental level, the laws of physics say you are immortal.

How about that for a superpower?

[This article appeared in print as "The Ups and Downs of Teleportation"]