Computers

Google's new quantum processor could soon outperform classic supercomputers

Google's new quantum processor...
Google has unveiled Bristlecone, a quantum computing processor with a staggering 72 qubits
Google has unveiled Bristlecone, a quantum computing processor with a staggering 72 qubits
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Research Scientist Marissa Giustina installs a Bristlecone chip
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Research Scientist Marissa Giustina installs a Bristlecone chip
An outline of the intended research direction of the Google Quantum AI Lab
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An outline of the intended research direction of the Google Quantum AI Lab
Google has unveiled Bristlecone, a quantum computing processor with a staggering 72 qubits
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Google has unveiled Bristlecone, a quantum computing processor with a staggering 72 qubits

With the quantum computing race heating up between Google, IBM and Intel, it feels like we're hurtling towards quantum supremacy, that milestone when a quantum computer outperforms a classical one for the first time. Bringing us ever closer, Google has now unveiled Bristlecone, a new quantum computer chip with the record-setting power of 72 quantum bits (qubits).

Traditional computers perform their calculations in binary, so every bit of data is represented as either a zero or a one. Thanks to the quirky science that is quantum mechanics, a qubit can be in a superposition of both, effectively representing both a zero and a one at the same time. That means the power of a quantum computing system scales exponentially – two qubits can represent four states at once (00, 01, 10 and 11), three qubits represent eight, and so on.

As a result, quantum computers are great at performing simultaneous operations, processing all of these states at the same time where classic computers would have to run through each in turn. That means that, theoretically, a quantum computer made with a 49-qubit chip (like Tangle Lake, a processor Intel unveiled at CES in January) could outperform our current best supercomputers at certain types of operations.

Google's latest chip prototype, Bristlecone, boasts a staggering 72 qubits. These are arranged in a square array, and get their quantum nature through superconductivity, which allows them to represent multiple states by conducting current in two directions at once.

But it's not just a matter of cramming in more qubits and putting them to work tackling the biggest mathematical problems in the universe. Qubits are notoriously fragile, and outside fluctuations can introduce memory errors that undermine the whole calculation. And these are hard to detect – as Schrödinger illustrated with his infamous feline friend, as soon as you peek in the box you collapse the wave function into one state or the other, garbling the information. That could be great for quantum encryption systems that alert you if someone tries to hack in, but it's not so helpful when you just want to read the output of a quantum computer.

Research Scientist Marissa Giustina installs a Bristlecone chip
Research Scientist Marissa Giustina installs a Bristlecone chip

To get around that problem, a few years ago the Google Quantum AI Lab developed a quantum error correction (QEC) technique, and demonstrated it in a system with nine qubits. The QEC works by checking combinations of data and measurement qubits, allowing the system to indirectly measure the information without affecting it. On the 9-qubit system, the method achieved error rates as low as 1 percent for readout, 0.1 percent for single-qubit gates and 0.6 percent for two-qubit gates.

The Google team is now aiming to achieve similarly low error rates on the Bristlecone processor's 72 qubits. To measure its performance, the researchers have developed a benchmarking tool that deliberately introduces a single error into the system, then compares the sampled output distribution to the results that a simulated classical computer came to.

The team says that eventually, the Bristlecone should be more than capable of reaching that watershed moment of demonstrating quantum supremacy. If it does manage to outperform a classical supercomputer, the processor could become the basis for building larger scale quantum computers.

Source: Google Research

10 comments
S Michael
I think I saw a pig fly the other day.
JimFox
Good grief! Science fiction becoming fact? Still, general use may be a long way off, after it is proven in scientific & military use.
JimFox
I think I saw a pig fly the other day. This intellectual comment has been said about almost every technology breakthrough. It adds NOTHING.
piperTom
The QEC [allows] the system to indirectly measure the information without affecting it. But Schrödinger's whole point was that there is IN PRINCIPLE no way to make any sort of direct or indirect way to get the information. If they have, indeed, found a way around it, then the principle is dead.
Rustin Lee Haase
It doesn't bode well when people say expressions like "as soon as you peek in the box you collapse the wave function into one state or the other". The "box" and the "state" are real, measurable, things found in this universe. A "wave function" is a mathematical expression found only in the separate "universe" of logic/mathematics. This kind of sloppy expression shows just how ignorant we actually are about quantum physics. :-)🦊
Gene Preston
There is a certain kind of probability problem in which a binary tree is constructed and each combination at the end of each branch on the tree is the product of probabilities and sum of values taking on either a 1 or 0 state working your way out to the branch. This kind of problem can be formulated in a cumulative distribution to get around the exponential time required form the tree. For example a power grid with 400 generators has 10^120 states of on and off. There are only 10^80 atoms in the universe. However this problem can be solved calculating the probability of all MW values in a fraction of a second on a PC. If you want to see how to do the convolution, its a simple shift scale and add process. The computer code to do this is listed in any of the RTS codes listed on my web page http://egpreston.com So maybe a standard pc can beat any quantum computer at this simple process if you just know how to code it to avoid the exponential growth tree formulation. Dr Eugene Preston, PE http://egpreston.com
mlnjr
Gene Preseton: "There are only 10^80 atoms in the universe" How can anyone possible know that?
Captain Danger
minjr this is from a 10 second google search "It is believed 74% of the mass of the Milky Way, for example, is in the form of hydrogen atoms. The Sun contains approximately 1057 atoms of hydrogen. If you multiple the number of atoms per star (1057) times the estimated number of stars in the universe (1023), you get a value of 1080 atoms in the known universe."
IvanWashington
if a 9-cubit system achieved readout error rates of 1%, how does that error rate performance compare with an equivalently powerful binary system?
Douglas E Knapp
ronbh, The Milky Way is NOT the known universe. It is one of about 300 billion galaxies. Two q-bits represent 0-3. Three q-bits are 0-7. Is that whole paragraph just wrong or is the author saying that q-bits work exactly like normal bits or binary math?