Quantum computing could literally change the world as we know it.
It could transform medicine, break encryption and revolutionize communications and artificial intelligence. Companies like IBM, Microsoft and Google are racing to build reliable quantum computers, while China has invested billions.
We are now one giant step closer to realizing that dream — quantum supremacy — with the announcement that a team of Russian-German scientists has created a quantum sensor that grants access to measurement and manipulation of individual two-level defects in qubits, SciTechDaily.com reported.
An ordinary computer chip uses bits. These are like tiny switches, that can either be in the off position – represented by a zero – or in the on position – represented by a one.
According to Wired, every app you use, website you visit and photograph you take is ultimately made up of millions of these bits in some combination of ones and zeroes.
Instead of bits, quantum computers use qubits. Rather than just being on or off, qubits can also be in what’s called “superposition” – where they’re both on and off at the same time, or somewhere on a spectrum between the two.
Take a coin. If you flip it, it can either be heads or tails. But if you spin it – it’s got a chance of landing on heads, and a chance of landing on tails. Until you measure it, by stopping the coin, it can be either.
Superposition is like a spinning coin, and it’s one of the things that makes quantum computers so powerful. A qubit allows for uncertainty.
The other thing that qubits can do is called entanglement, Wired reported.
Normally, if you flip two coins, the result of one coin toss has no bearing on the result of the other one. They’re independent.
In entanglement, two particles are linked together, even if they’re physically separate. If one comes up heads, the other one will also be heads.
It sounds like magic, and physicists still don’t fully understand how or why it works. But in the realm of quantum computing, it means that you can move information around, even if it contains uncertainty.
You can take that spinning coin and use it to perform complex calculations. And if you can string together multiple qubits, you can tackle problems that would take our best computers millions of years to solve.
If you ask a normal computer to figure its way out of a maze, it will try every single branch in turn, ruling them all out individually until it finds the right one. A quantum computer can go down every path of the maze at once. It can hold uncertainty in its head.
Today, superconducting qubits are based on the Josephson junction. That is the kind of qubit IBM and Google used in their quantum processors, SciTechDaily reported.
However, scientists are still searching for the perfect qubit — the one that can be precisely measured and controlled, while remaining unaffected by its environment.
The key element of a superconducting qubit is the nanoscale superconductor — insulator — superconductor Josephson junction.
According to Scientific American, a Josephson “tunnel” junction is made by sandwiching a thin layer of a nonsuperconducting material between two layers of superconducting material.
The devices are named after Brian Josephson, who predicted in 1962 that pairs of superconducting electrons could “tunnel” right through the nonsuperconducting barrier from one superconductor to another.
He also predicted the exact form of the current and voltage relations for the junction. Experimental work proved that he was right, and Josephson was awarded the 1973 Nobel Prize in Physics for his work.
Modern techniques do not allow to build a qubit with 100% precision, resulting in so-called tunneling two-level defects that limit the performance of superconducting quantum devices and cause computational errors.
Those defects contribute to a qubit’s extremely short life span, or decoherence.
Tunneling defects at the surfaces of superconductors are an important source of fluctuations and energy losses in superconducting qubits, ultimately limiting the computer run-time.
The more material defects occur, the more they affect the cubit’s performance, causing more computational errors, the researchers noted.
The new quantum sensor grants access to measurement and manipulation of individual two-level defects in quantum systems.
According to Prof. Alexey Ustinov, Head of the Laboratory for Superconducting Metamaterials at NUST MISIS and Group Head at Russian Quantum Center, who co-authored the study, the sensor itself is a superconducting qubit, and it allows the detection and manipulation of individual defects.
The study may open avenues for quantum material spectroscopy to investigate the structure of tunneling defects and to develop low-loss dielectrics that are urgently required for the advancement of superconducting quantum computers.
The latter could mean more efficient products – from new materials for batteries in electric cars, through to better and cheaper drugs, or vastly improved solar panels. Scientists hope that quantum simulations could even help find a cure for Alzheimer’s.
There are also rumours that intelligence agencies across the world are already stockpiling vast amounts of encrypted data in the hope that they’ll soon have access to a quantum computer that can crack it.
The study was conducted by NUST MISIS (The National University of Science and Technology), Russian Quantum Center and the Karlsruhe Institute of Technology, and was published in npj Quantum Information.
Sources: SciTechDaily.com, Wired, Scientific American