A quantum computer is a computing system that performs data operations by the physical phenomena of superposition, entanglement and interference.
Quantum computers produce data based on quantum properties, as opposed to digital computers which provide data encoded in bits. Large-scale quantum computers use integer factorization algorithms or quantum system simulation to resolve problems faster than any other classical computers.
A common demonstration of this is Simon's Algorithm - a mathematical problem devised by Daniel Simon which can be solved exponentially faster by a quantum computer than by a conventional computer.
The Launch of Google's Quantum Computer
In early 2009, Google announced its collaboration with Canadian company, D-Wave Systems, Inc and NASA to work on a project using a 512-quantum bit (qubit) D-Wave Two quantum computer with the objective of optimising solutions currently outside of the capabilities of conventional computers. In particular, Google hoped its $10 million investment to apply would fund research into the enhancement of human signal interpretation, whilst NASA’s interest was in the formation of a more comprehensive understanding of our universe.
Following this, in May 2013 the trio launched the Quantum Artificial Intelligence Lab that operates on machine learning, the process through which computing systems observe the information patterns to enhance their outputs. The first public update on the lab’s progress was made via a highly anticipated short film released at the Imagine Science Films Festival October that year. The video explained exactly what they understood quantum computing to be and the proposed applications of the installed D-Wave quantum computer.
Using Google’s Quantum Computer
As mentioned previously, Google’s foremost aim was in the advancement of human signal recognition. An example of such is the "wink detector" algorithm designed by Google as part of their wearable electronics project, Glass. The algorithm was intended to differentiate between involuntary and intentional winks, but proved to be very inaccurate. Google hope to develop a better version through their newly acquired quantum technology.
Other key areas where the power of Google’s quantum computer could be harnessed include the following:
- Jet aircraft designs
- Satellite systems
- Drug discovery
The D-Wave 2X model purchased by Google employed four 128s qubit chips giving a total of 512 qubits of algorithmic capacity. It was declared by D-wave that this computer was revolutionary due to the employment of quantum entanglement by their chips as well as superposition, a phenomena that enables the qubits to take on values of both 1 and 0 simultaneously, thus dramatically reducing processing time.
However, despite the clear support of Google’s investment, many scientists remained unconvinced by the computer’s supposed capabilities. Although research published in 2011 demonstrated that the chips were capable of quantum physics, D-wave had no evidence to suggest that these processes were being used correctly to result in the promised processing speeds. Furthermore, as highlighted by Scott Aaronson of the Massachusetts Institute of technology, the traditional computers used to compare the running times were not optimised to solve the specific algorithms as was the case for the D-Wave machine, leading to much speculation regarding the device’s claimed prowess.
Google’s Quantum Breakthrough
In March this year, any doubts surrounding the rationale behind Google’s partnership with D-Wave were silenced by the unveiling of Bristlecone; the world’s largest quantum computer processor to date. Bristlecone boasts a 72 qubit gate-based superconducting system, breaking the previous 52 qubit record held by IBM. The impact of this achievement lies in the race to quantum supremacy, where supremacy is defined as the ability of a quantum computer to perform a calculation unable to be solved by conventional computers. As of yet, no quantum computer has succeeded in achieving this crucial feat due to the enormous power required to do so and therefore the dramatic increase in qubits of Bristlecone is seen as a significant step towards this goal.
However, power is not the only limiting factor, supremacy is also dependent on a sufficiently low error rate. Google predicts that the bench mark for this factor is a two-qubit error below 0.5%. The company’s previous 9 qubit processer achieved an optimum error rate of 0.6%, requiring a further enhancement of 0.1%. This decrease may seem small, but it poses a significant technical challenge due to the tendency of an increase in error rate with processing power. Hence, the focus of current research is devoted to retaining and further refining the accuracy of their lower power processer combined with the world-leading power of Bristlecone. Google have stated they are “cautiously confident” that this will be achievable and that the race to quantum supremacy will soon be won.
Conventional computers, including supercomputers, require substantial time to process large quantities of data. Scientists have now developed a computer that harnesses principles of quantum theory with the promise of performing calculations not only faster but also outside of current computers’ capability.
These quantum computers take advantage of processes such as quantum entanglement and quantum superposition to represent information in qubits.
With the evolution of Google’s quantum computer, the scientific world is on the edge of an era of quantum supremacy, the applications for which include the enhancement of human/computer interaction and the rapid encoding of extremely sensitive data. It is evident, that the future of computing lies with quantum computers.
Sources and Further Reading
This article was updated on 19th December, 2018.