Two groups of physicists, one from Austria and the other from the United States, succeeded for the first time in teleporting atoms. Until now teleportation has only been seen in photons. The results could be a huge step towards building a macroscopically sized quantum computer.
Quantum teleportation: in the first step two conjugated ions (A and B) are created, and then a third ion (P) is created in the state in which you want to teleport. In the third step A and P there is an interaction between A and P, and its results are sent to ion B. In conclusion, the state of P is sent to B.
Two groups of physicists, one from Austria and the other from the United States, succeeded for the first time in teleporting atoms. Until now teleportation has only been seen in photons. The results could be a huge step towards building a macroscopically sized quantum computer.
In quantum teleportation, the sender, usually referred to as "Alice", instantly transmits information about the quantum state of a particle to the receiver, usually referred to as "Bob". The uncertainty principle limits Alice's ability to know the exact quantum state of her particle, but another phenomenon of quantum mechanics, called entanglement, allows her to send the quantum state to Bob.
The coupling allows two particles to be bound to each other in a much tighter relationship than classical physics allows. If two particles are conjugated to each other, the state of one can be determined by measuring the other. For example, two particles may be coupled, so that the spin of one of them is "down" and the spin of the other is "up" or opposite. Another phenomenon in quantum mechanics allows a particle to be in superposition in these two states at the same time.
David Wineland and his colleagues at the National Institute of Standards and Technology (NIST) in Colorado began their task by creating a single trapped beryllium ion, which is in a superposition of spin up and down simultaneously. Lasers were then used to launch these quantum states into a second ion with the help of a third auxiliary ion (see diagram). NIST's method was based on the ability to move the trapped ions.
Rainer Blatt and his colleagues from the University of Innsbruck performed a similar experiment using trapped calcium ions. However, instead of moving the ions, they "hid" them in different internal positions.
The success of a teleportation experiment is measured by its reliability value, a number that shows how accurately the first quantum system was recreated in the second. Both groups, from NIST and Innsbruck, achieved a reliability value of about 75%. For comparison, teleportation methods, which do not use coupling, cannot reach a reliability value higher than 66.6%.
"Success in teleporting the quantum state of an atom is important and exciting for the purposes of building macroscopic-sized quantum computers," Ballett told Physics Web. "The method for quantum processing of information can be applied in combination with some kind of interface system, the nature and construction of which is still being studied, to link different components in a quantum computer."
Translation: Dikla Oren
The super-fast future of computers
One of the scientists who participated in the ground-breaking experiment for telekinetic launch in the style of Star Wars (Teleporting) estimates that in 2035, ultra-fast quantum computers will be operating. "Moore's Law states that every 18 months the memory, speed and other performance characteristics of computers will double" explains Dr. Ping Kui Lam. "In a few years the transistors will be reduced to the size of single atoms and then we will have to face the quantum theory".
Dr. Lam, an Australian physicist, together with his colleague from the Australian National University Warwick Bowden, made a breakthrough in the study of light rays in 2002. In an experiment they conducted, they managed to make a light beam disappear and bring it back, in a process known as "entanglement". Since 1998, when it was proven that this was possible, the race for the telekinetic launch of a light beam has been going on in 40 different laboratories. Following their success, Bowden and Dr. Lam won world recognition and an award from the British consul, which also included a trip (by plane and not on the light rays) to Britain, where they shared their secrets with other scientists.
"Our experiment in itself has no practical meaning for the common man" sneers Dr. Lam. "However, the joint international efforts may yield significant results." Quantum physics has so far not yielded many practical applications, but "many physicists believe that the quantum revolution is near". In the long run, quantum physics will be able to contribute to many applications - from extremely sensitive sensors to computers and communications.
The government and the military will benefit from secure communication using quantum encryption, where the key is built from single photons. "Quantum encryption is already in use," says Dr. Lam, "but is still not very popular. This will change in the coming years." In the last year, Dr. Lam, in collaboration with the Department of Quantum Optics of the Australian National University, developed a communication protocol known as "secret sharing". This protocol offers many advantages to companies, banks and security forces because within it the secret information is sent to several parties and only after the identity of most of them has been verified will the information be revealed.
However, those who dream of launching themselves to remote places in the style of Dr. Spock and Scott will be disappointed. "At the moment the issue is in its infancy and only data can be sent" - that is, e-mail and not people. However, in 30 years, quantum physics is expected to flourish, says Dr. Lam, "and information technology people, mathematicians and doctors will be required to rethink. In return, they will benefit from super-fast quantum computers."
Translation: Benny Ran
One moment you are here, and at the same moment - there
By Yitzhak Ben Israel, Haaretz, 28/6/04
Scientists have succeeded in teleporting atoms: "disappearing" an atom and causing it to instantly appear elsewhere. In principle it can work with humans too
Last week it was published in the journal "Nature" that two groups of scientists succeeded in teleporting an atom, that is, transferring the properties of an atom in the laboratory to another atom, distant from it, without the properties making the way between them.
Modern technology provides many means for moving objects and people from one place to another: cars, trains, ships, planes, spaceships, and the like. The more advanced the technology, the shorter the transition time. Can it be shortened to zero? Is it possible, for example, to transport a book from Tel Aviv to New York at a speed greater than the speed of a jet plane? From the speed of the spacecraft? In fact, already today it is possible to transfer a book at a much greater speed, almost at the speed of light. More precisely, we do not transfer the object itself (book) but the information contained in it. This can be done by scanning the book in Tel Aviv and transmitting the information contained in it with radio waves (which, as we know, move at the speed of light). At the other end (New York) the information will be recorded, and if we wish, it will be printed immediately in the form of the original book.
In terms of classical physics, there is no obstacle to repeating this process with any "object", including animals: all we have to do to "send" our Tel Aviv house cat to our aunt in New York is to scan the state of the atoms that make up the cat, write down all the information The north of them, send this information by radio to New York, and make sure that on the other end there will be a machine that will build a new cat from the atoms provided to it. But in any case, even if we manage to do this, we will not be able to move objects from one place to another at a speed greater than the speed of light.
indeed? Modern physics rejects this assumption, and it is not a purely theoretical claim but an experimentally tested claim: as mentioned, the scientists at the American National Standards Institute in Boulder, Colorado, and at the University of Innsbruck in Austria succeeded in "disappearing" an atom and causing its immediate appearance elsewhere without any time passing between the object's disappearance at the "launch" point ” and between his appearance at the destination. For those who remember the series "Star Trek", here is the fulfillment of what until recently was science fiction.
Einstein or Bohr
To understand what happened in the experiment, we must go back more than 70 years, to the first quarter of the twentieth century. Physics then knew two revolutions: relativity and quantum theory. The first was born in the mind of the young Dr. Albert Einstein; With the heroes of the second revolution, we can name, again, Einstein, along with Max Planck, Werner Heisenberg, Erwin Schrödinger and especially Niels Bohr. Planck gave the signal (which won him the Nobel Prize in Physics) by raising the hypothesis that a hot body does not emit energy continuously but in batches ("quanta"). Einstein used this to explain for the first time the effect of the formation of electricity when metal is illuminated (for which he won the Nobel Prize), Bohr was the first (another Nobel) to try to use these ideas to explain the structure of the atom, while Heisenberg and Schrödinger gave quantum theory its familiar form today ( They also later received a Nobel Prize).
From its beginning, a sharp debate developed between physicists about the meaning of quantum theory and the correct way to interpret it. The debates between Bohr on the one hand and Einstein on the other were decided by scientific "public opinion" in favor of the interpretation of Bohr's group, which has since been called the "Copenhagen School".
At its core, this is a metaphysical debate about the nature of reality: the opposing sides agreed among themselves that quantum theory describes well what can be measured in the laboratory. Moreover, since its formulation three quarters of a century ago and until today, none of its predictions have been found to be wrong. But what follows from her basic assumptions about the nature of reality?
To demonstrate this, we will consider a single atom. According to quantum theory, it is not possible to predict with certainty both its location and its speed. If we know one size with absolute precision we will know nothing about the other. We can only know both approximately (this is the essence of Heisenberg's uncertainty principle). So, Bohr asked, if we can never know both together, who guarantees us that they do exist together? Maybe the atom has no place at all and is only created at the moment of measurement?
Moreover, according to Bohr, an atom has "location" only in relation to an experimental set-up designed to measure space, and it has "velocity" only in relation to an experimental set-up designed to measure speed. And since two such experimental setups cannot exist together, "place" and "speed" cannot be sealed at the same time. Bohr saw this as an extension of the theory of relativity: place and speed (and in fact all the dynamic properties of a material body) are relative quantities not only in relation to the system of axes in which the measurement is made, but in relation to the entire world and especially to the experimental set-up.
Today, looking back, the two rivals, Einstein and Bohr, stand out as those who helped others to understand the deeper meanings of the New Torah. In a famous article that Einstein wrote in 1935 together with his two colleagues Podolsky and Rosen, he claimed that the profound meaning of Bohr's claim is that quantum theory allows for "action at a distance", meaning that an event that occurs in one place can immediately affect another event - contrary to what is expected From the principles of relativity. In Bohr's reply to the article, he claimed that it is not a "mechanical" effect through force or any physical field, but "an effect on the very logical conditions that define the type of possible predictions regarding the future behavior of the system" being measured. Placing an appropriate experimental set-up affects the results of the experiment and therefore appears as if it affects "from a distance".
For Einstein this was enough to regard Bohr's interpretation with suspicion, which he called "Talmudic nonsense." He expected that over time it would be revealed that it was not true. But as the years passed and the quantum theory stood the test of experiment, the wheel turned: maybe both Bohr and Einstein were right? Maybe it's really possible to influence from afar?
A revolution in computing
The revolution followed the work of the Irish physicist John Bell who showed in 1962 a way to test this experimentally. By the way, Bell's work is based on the physicist David Bohm, who escaped in the early XNUMXs from the anti-communist witch hunt of Senator McCarthy in the USA. Boehm spent several years at the Technion, where together with his Israeli student Aharonov he discovered the Boehm-Aharonov effect, which also refers to the effect "at a distance".
About twenty years after Bell, in 1984, Alain Aspect and his friends at the Sorbonne succeeded for the first time in conducting an experiment that proved that remote action is possible. From here the road to teleportation is short, that is, to the idea of moving objects from one place to another in zero time. First, such experiments were carried out with light particles (photons), and now, as mentioned, with the atom.
It is important to emphasize that in terms of quantum physics there is no difference between light and matter, and the experiments with light particles are easier to perform (in 1997 even teleportation of light particles to a distance of about 10 km was demonstrated), but experiments with a material body have at least a considerable psychological weight. It is also important to emphasize that the atom in the teleportation experiment did not pass the way between the launch point and the destination. It disappeared in one place, and its properties appeared in another atom that was at the destination. It is therefore a teleportation of properties and not of "matter".
Will we be able to travel to the USA in the future in the way that was loved by the heroes of "Star Trek"? Can we get into a special booth at Ben Gurion Airport and show up immediately at Kennedy Airport without losing time and without jet-lag?
Basically the answer is yes, but it may be a very long time before it becomes practical. The main reason for this is that a large (macroscopic) body has a huge number of atoms, each of which behaves in a way that is almost independent of the other atoms. In order for us to make such a body disappear in one place and cause all its properties to be copied perfectly to a body located in another place, all its atoms would have to behave in the same way. To do this we will have to completely isolate the body from external influences, including cosmic radiation, and from internal influences, including collisions between the atoms in the body and among themselves, and today we have no idea how to do this.
If so, will everything described above have any effect in the near term on our lives? Definitely yes. You can use the exact same phenomenon to perform many calculations at the same time. The computers we use today are based on manipulating the movements of electrons. But if the electron is not a "body" whose position is precisely defined, and it is possible to transfer the information it carries to another place in zero time, what prevents us from performing several calculations at the same time?
Already today several groups in the world are working very vigorously on the application of this principle in computer technology. There are already primitive devices capable of performing limited calculations. When the first quantum computers appear in the commercial world (some estimate that this will happen 20-10 years from now), the current computers will be seen as extremely primitive. According to some predictions, the speed of our computers today will be less than a billionth of a billionth of these computers.
Prof. Ben Israel is the head of the "Tel Aviv Workshop for Science, Technology and Security" at Tel Aviv University
