Early theories of 'quantum steering' are informing today's researchers in their quest to establish secure quantum teleportation and with it the un-hackable communication networks of tomorrow.
Teleportation is here! However, with no William Shatner as Captain Kirk in sight, it might not be quite what you’ve been eagerly anticipating. Don’t panic! Whilst we’re not yet at the stage where we can teleport humans (sorry to get your hopes up with the nostalgic picture, above), researchers have recently demonstrated the prerequisites for secure quantum teleportation.
For the first time, a group of researchers including Dr Laura Rosales-Zarate and Professor Margaret Reid from Australia’s Swinburne University of Technology, together with a team from China and Europe, has established the precise requirements needed for the instantaneous transport of quantum information.
Quantum steering anyone?
Quantum teleportation heralds the arrival of a potential new form of communication that’s essential for a future quantum Internet allowing information to be transmitted with absolute security. It entails the transport of quantum information, such as the exact state of a photon or electron, without moving that actual particle. In order to achieve this, an ‘entangled state’ must be shared between the source and destination locations, referred to as ‘Alice’ and ‘Bob’ (they’re not making this up, you know), creating a ‘quantum channel’ between the two sites.
The mechanism involves a phenomenon known as ‘quantum steering’, a theory first proposed by Albert Einstein and Erwin Schrödinger in 1935 which states that a measurement has an immediate ‘steering’ effect on another distant quantum state. In quantum mechanics, this means that if one party performs a measurement on one system, different outcomes can lead to different states for another system.
The precise requirements demonstrated by today’s researchers in achieving quantum teleportation focuses on the ‘entangled state’ referred to above and involves a special kind of quantum entanglement called Einstein-Podolsky-Rosen steering, a theory based on Einstein and Schrödinger's original ‘quantum steering’. Using this theory, the quality of the transported state can potentially be ‘perfect’, allowing for messages to come through clearly and securely.
Commenting on their work, published in Physical Review Letters, Prof Reid said: “Teleportation works like a sophisticated fax machine, where a quantum state is transported from one location to another. Let's say 'Alice' begins the process by performing operations on the quantum state – something that encodes the state of a system – at her station. Based on the outcomes of her operations, she communicates (by telephone or public Internet) to 'Bob' at a distant location, who is then able to create a replica of the quantum state.”
No more eavesdropping
Using quantum entanglement, people will be able to send information across large distances free from the fear of eavesdroppers; although what this will mean for any future so-called Snoopers’ Charter with its implications for data interception opens up a whole new can of worms. We’re not going there today. What we’re hailing are the building blocks of the un-hackable communication networks of tomorrow.
Quantum teleportation isn’t brand new in and of itself. Scientists first achieved quantum teleportation last year and have been improving the process ever since, but they still hadn't managed to send a message that didn't come out garbled and incoherent on the other side - until now.
“The problem is that unless special requirements are satisfied, quantum mechanics demands that the state at Bob's end will be 'fuzzed up',” explains Prof Reid. “The beauty is that quantum mechanics guarantees that a perfect state can only be transported to one receiver. Any second 'eavesdropper' will get a fuzzy version.”
The researchers have shown that by employing Einstein-Podolsky-Rosen steering - the very special form of quantum entanglement - Alice and Bob can avoid getting all ‘fuzzed up’.
“Only then can the quality of the transported state be perfect,” Prof Reid adds.
Beam me up, Scotty (really)
Elsewhere in the field of teleportation, German engineers have created a machine which can scan an object - destroying it in the process - and then transmit it over the Internet, recreating it anywhere in the world using a 3D printer. Is this what we’ve been waiting for? Can my destroyed body really be beamed anywhere around the world? Not quite, but it's a start.
Named ‘Scotty’ (of course), engineers at the Hasso Plattner Institute in Germany have successfully relocated inanimate physical objects across distances. Scotty is a simple self-contained appliance that consists of an off-the-shelf 3D printer that has been extended with a three-axis milling machine, a camera and a microcontroller for encryption/decryption and transmission.
Users place an object into the sender unit, enter the address of a receiver unit and press the teleport button. The sender unit now digitises the original object layer-by-layer. It shaves off material using the built-in milling machine, taking a photo using the built-in camera and encrypts each layer using the public key of the receiver before transmitting it.
The receiving unit decrypts the layer in real-time and starts printing right away. Users therefore see the object appear layer by layer on the receiver side just as it disappears layer by layer at the sender side. Scotty is different from previous systems that copy physical objects in that its destruction and encryption mechanism guarantees that only one copy of the object exists at a time.
Whilst people won’t be queuing up to beam themselves across the Internet any time soon, does Scotty mark the beginning of a new era; the first prototype of a teleportation machine that can effectively relocate an object from one location to another? Make it so.