It’s Monday. It’s raining. It’s cold. You are about to make the same choice as thousands of fellow workers: today you will drive to work. You sigh with resignation: there is a trivial linear relationship between rain and traffic, and you know that today it will take you longer than usual to get to work.
There is a fixed thought that pops into your head every time you know you’re going to be stuck in traffic for who knows how long: “How nice it would be if I could teleport directly to my destination”. This time is no exception, and while you’re waiting for the green light you begin to fantasize that someone out there can operate a machine, full of buttons (but not too bulky), that picks you up from home and makes you arrive directly in your office. How convenient!
Yes, kind of like what happened on Star Trek. “How long will it take scientists, physicists and engineers to build such a contraption? We’ve made so much progress, how difficult it can be to build a teleportation booth!”. Traveling by car to your destination, you begin to reason about which route is best for you. There are several, from the shortest and busiest to the long or winding, but usually with less traffic. And while the choice is still in a confused and indistinguishable overlay of possibilities in your head, you go back to the teleporter and wonder how Star Trek worked. After all, it’s the most famous one in the history of science fiction.
In each episode, a squad of men would enter the teleportation booth, each in his place, and, in a beam of light and glow, would be dematerialized from the spaceship’s cabin and rematerialized there, on the surface of the planet to be explored. A trick that allowed the screenwriters to stay within the budget, without having to film landings and takeoffs of the Enterprise at every episode. And, at the same time, a synthesis and confirmation of the imagery of how a teleporter should work. A machine reads and stores all the information about an individual and transforms it into energy, then, with a reverse process, it reconverts that energy to the shape of the individual.
Now, leaving aside for a moment whether or not this is feasible in reality, if teleportation worked this way it probably wouldn’t be as fast as the TV shows have led us to believe. Sure, it would take you a few microseconds to get to work by teleporting from home, but if we want to travel the interstellar space, we won’t get there fast even with teleportation. If there is an “energy beam” that has to travel from one point to another, it is forced to travel at most at the speed of light. For example, do we want to teleport to the closest star to the Sun, Proxima Centauri? Well, then teleportation – as we have described it so far – leaves us traveling for over 4 years.
In Star Trek faster-than-light movement and communication are established technologies, but we still have no indication that we will ever break through the invisible, impassable wall of light speed.
Nevertheless, after all, you’re not interested in exploring new worlds. You don’t want to go where no man has gone before, you just want to get to work and spare yourself the traffic line! The idea still appeals to you. In fact, you could even live on the other side of the planet and get to work on time every morning. You could live in California and work in London! A dream!
Of course, it would be necessary to make sure that the system works, before installing it in every company or office. It would be unpleasant to find yourself with half a body teleported there and the rest still at home… You seem to remember that some science fiction author had imagined a head, still working and talking, arrived at its destination without its body. Fonte:Page You immediately dismiss this extreme situation as pure fantasy. But what if, while the machine is reading the information of the individual to be transported, something foreign is being “scanned” along with the traveler? “The Fly” Fonte:Mosca , a movie from several decades ago, was the story of a man who found himself exiting the teleportation booth with his own DNA fused to that of a fly.
And it is here that the enlightenment comes to you: the real difficulty of a “Star Trek” teleportation lies in coding exactly what the individual to be teleported looks like. And by exactly we mean down to the last characteristic of every subatomic particle of the individual. Once past this hurdle, what does it take to send the information to its destination and reconstruct the traveler?
Well, if it weren’t for Heisenberg’s uncertainty principle, which effectively makes all of a particle’s characteristics unknowable at once to any small precision, it could be done. All it takes is memory space, computational speed, and energy. More than we will ever be able to get through. It is estimated that to describe an atom you need 100 bits, the fundamental units of computer memory. In each human being there are approximately 1028 atoms (that is 10 billion billion billion). Fonte:Castellani So for each individual it should be enough to have a hard disk with a storage capacity of 100×1028 bits. The hard disks we use today are at most of the order of terabytes, or have a capacity of 8×1012 bits: it would take an extra 1018 (one billion billion) to contain the information relating to a single human being to be teleported. A similar reasoning can be applied to the processing time: to process all the information describing a single individual, with current calculators, would take about 4.8 trillion years. Fonte:Leicester If we keep in mind that the universe has a little more than 13 billion years, it is clear that the task is impossible. Even the energy needed for such a teleportation would be something currently unthinkable. It would depend on the speed of data transmission: if we wanted to shorten the time it would be necessary to increase the energy involved. But even with the fastest current data transmissions it would take an energy of the order of 10 trillion gigawatt hours: that’s the Italian electricity requirements for the next 30 million years, according to the current consumption. Fonte:Terna
Yet, up to this point, one can still imagine that scientists will invent new calculators or new ways of doing calculations, and sooner or later they will be able to store and process all the information needed for human teleportation. Maybe they will be able to use the energy coming from the Sun in a much more efficient way, and multiply disproportionately the energy available to mankind. Less probable is to bypass Heisenberg though. Yet, maybe in the next 100 years? Who knows what advances in science and technology await us?
Lost in these thoughts, increasingly inclined to accept the impossibility of human teleportation, you turn on the radio and look for something to keep you company.
It’s your lucky day though, because they are talking about a successful teleportation experiment on the radio. Your initial enthusiasm at hearing the news, however, is dampened as you listen to the details of the experiment. This is not a teleportation of human beings, but quantum teleportation, a technique with which you can instantly “transfer” one or more particles to a distance as large as you like.
The fundamental difference between quantum and human teleportation is that the latter transfers neither matter nor energy. What is transferred is the state of a particle, alas, information. The result of quantum teleportation is like a kind of mapping, but you don’t know what the map looks like until you arrive at the end of the transport.
Since the first experimental proof in 1997 Fonte:Dik , research groups around the world have focused on developing the best technology to handle quantum teleports. Photons, electrons, even some ensembles of atoms have been successfully teleported. They have used satellites in orbit to teleport quantum states at a distance of more than 1200 km. Fonte:Liao The interest for this technique is due to the fact that quantum teleportation is one of the leading technologies for the construction of new computers. Communities of physicists are already imagining new security protocols, new computers, new forms of communication: all this is not science fiction, it is something that can actually be achieved and within reach of our current knowledge.
The principles of quantum physics are already exploited in the field of quantum cryptography. The concept of being able to exchange messages indecipherable by those who do not have the right key to read them is as old as our species. However, it takes on new strength if the key is made of quantum, that is, composed of particles subject to quantum laws. In cryptography the superposition principle is applied: until a measurement is made on the state of a particle, it will be in a superposition of possible states, i.e. we cannot know the state of a particle until we observe it. Once observed, however, the measured state takes on a unique and definite value: there is no turning back. Since measuring the properties of a particle changes the particle itself, an unauthorized observer trying to sneak in and read a communication would be immediately discovered by both sender and receiver. Quantum cryptography would also become a necessity if quantum computers were to be used: any classical key would be too easy to reveal for anyone with the computational speed that a quantum computer can provide.
Transforming the minimum unit of information of the classical computer, the bit, which can have only state 0 or state 1, in the minimum unit of information of a quantum system, the qubit (quantum bit), which can keep in memory a superposition of the two states, allows in fact to increase the computational capacity by orders of magnitude. Not doubling, tripling, or tenfold the computational speed: much more! A 53-qubit quantum computer prototype from Google, Sycamore, in a 2019 experiment performed in 200 seconds a calculation that the most powerful classical supercomputer currently in use would have taken 10 thousand years to complete. Fonte:Arute
The difference is astounding. So is the difficulty of construction and management, though. The qubits must work without coming into contact with any other particle, otherwise there is the loss of that superposition that gives the advantage over the classic bit.
Together with the search for the quantum computer, there is the search for a quantum internet. If you want to build a quantum internet, not only the machines must store and process information using qubits, and therefore quantum superposition, but the connection system between the various machines must be rethought in order to “move” these qubits. The new data transmission will be based on quantum correlation and on the possibility to teleport the state of a particle or an ensemble of particles from a machine to another.
The quantum correlation, also known as entanglement, is obtained by forcing a relationship between two particles, so that they behave as if they were no longer independent of each other but a single entity. This means that once you measure a particle size, for example spin of an electron or polarization of a photon, you can be sure that of the second particle you will get the corresponding measure. This means that you can predict instantaneously the result, by simply measuring a second entangled particle. It does not matter if the two measurements are made on the same table, or one in a laboratory on Earth and the second one on Proxima Centauri. By the way, this concept deeply disturbed Einstein and other physicists of the twentieth century, because it forces a profound change in the perspective with which we look at nature and the way it speaks to us.
By exploiting quantum correlation, information can be transferred instantaneously over long distances on command. But can we communicate at speeds faster than light? No – you can almost see the physicist on the radio smiling under his moustache while explaining the paradox – the speed of light remains undefeated even when we try to communicate with entangled particles. It is true that if we measure two particles in quantum correlation they give corresponding results, but in the laboratory on Proxima Centauri they still should know what kind of measurement has been done on Earth, and this communication would travel according to classical channels, therefore at the speed of light.
Technical obstacles are not trivial when it’s about to realize a quantum internet network. The current experiments are able to carry information through quantum channels for distances of the order of a few tens of kilometers through fiber optics. Fiber is used because experiments often use photons as entangled particles, and also because fiber optics is part of an infrastructure already in place and commonly used. The current record for quantum teleportation by optical fiber is 44 kilometers, from an experiment conducted by the Fermilab and the California Institute of Technology (Caltech) in late 2020. Fonte:Fermilab Fonte:Quantum
This car trip was more interesting than usual, wasn’t it? You had to wait in traffic and it took you longer than usual to get to work. But in the meantime, you got lost in fantasizing about the ethical implications of human teleportation and mulling over how quantum physics is profoundly different from the physical reality we’re used to perceiving with our senses. Yet, as you get out of your car to head to your office, you reflect on the fact that you’ll find about half of your colleagues at headquarters today. The others won’t leave their apartments. In the past two years we haven’t even needed science fiction to teleport us to work. Or to school. We’ve all experienced surrogate teleportation, which doesn’t broadcast our bodies, but our minds. We’ve connected through a digital device and an internet connection to the same virtual room inhabited by one or more people. We held meetings and interviews and took or delivered courses and classes, all simply from the comfort of our homes. And it takes only one click. And a decent connection. And a good camera too.
The benefits of remote working were immediately visible: cut down on commuting time, better time management at home (do you remember how many washing machine loads you put on between meetings?), and coffee breaks with our family. However, remote working has its severe downsides too. The most trivial difficulty to foresee was the lack of tranquility or the means and space to continue working or studying with the effectiveness and efficiency that the dedicated place offers. Another difficulty, more insidious and perhaps less expected, is the fatigue involved in interacting through the screen. Millions of years of evolution have made us a splendid social animal, one that interprets others not only from words, but also through nonverbal language. Here, we’ve discovered how exhausting it is to grasp the countless nuances of nonverbal language when the only way to do so is to peer at an image on a screen, sometimes even at low resolution, and listen to voices through speakers or headphones (sometimes jerky because the speaker or listener has an unstable or busy connection).
We’ve used this surrogate teleporter so many times, and we’ll continue to do so. It does what it’s supposed to: it resets distance and travel time to zero. At least within the insurmountable limit of the speed of light. However, as you walk into the office, sit down at your desk and turn on your PC, you can’t help but think how that car ride this morning gave you a chance to think and reflect and get lost in your thoughts. It gave you, in essence, the chance to slow down. In a world with zero distance and zero time to spare, where we are happy to declare that every minute of our day is packed with tasks to be accomplished, you wonder if teleportation is something that you really want.
You wonder if travel is really worth it… without enjoying the journey.