Google has claimed “Quantum Supremacy” in its recent Nature post, stating that its newest creation Sycamore could outperform all classical computers. This news comes just a month after its research work was accidentally leaked online.
Origin of Quantum Computing
The origin of Quantum Computing concept dates back to 1981 when Richard Faynman at MIT had proposed its basic model with exponential problem-solving capabilities. Around 10 years later, a special algorithm called Shor algorithm took birth which later became the basis for a 2-bit quantum computer in 1998.
Two decades later in 2017, IBM showcased its first commercially viable quantum computer and thus began the rat race to establish “Quantum Supremacy” in the rapidly evolving world of supercomputing.
IBM’s Counter Claim on Google’s Quantum Supremacy
IBM has now quashed Google’s claim of having accomplished “Quantum Supremacy” with its creation of Sycamore Quantum processor. The search-engine giant has claimed that Sycamore is capable of performing a specific task in 200 seconds as opposed to 10,000 years taken by the world’s best supercomputer.
IBM researchers Edwin Pednault, John Gunnels, and Jay Gambetta have disputed Google’s claim in their recent blog post, stating that their own Summit supercomputer is capable of solving the problem in just 2.5 days while using performance-enhancing techniques with hard-drive storage.
Unlike the classical computer which processes 0s and 1s to generate an output, the quantum system uses qubits (a combination of both 0s and 1s) to enable exponential levels of problem-solving capabilities.
This exponential computing capability is based on the concept of Quantum Superposition or Quantum Entanglement wherein the quantum state of each particle affects the other as their existence is intertwined or superposed even when separated by great distances.
IBM’s Counter Claim – Explained
Substantiating its counter claim, IBM’s blog post states as follows:
“This is in fact a conservative, worst-case estimate, and we expect that with additional refinements the classical cost of the simulation can be further reduced.
“First because… by its strictest definition the goal has not been met. But more fundamentally, because quantum computers will never reign ‘supreme’ over classical computers, but will rather work in concert with them, since each have their unique strengths.
“However, classical computers have resources of their own such as a hierarchy of memories and high-precision computations in hardware, various software assets, and a vast knowledge base of algorithms, and it is important to leverage all such capabilities when comparing quantum to classical.”
Google’s Reaction to IBM’s Counter Claim
Reacting to IBM’s argument, here is what the Google spokesperson reiterated in support of the company’s claims to Quantum Supremacy:
“With Sycamore we’ve demonstrated that we’re now in the NISQ [Noise Intermediate-Scale Quantum] era, performing on real hardware a computation that’s prohibitively hard for even the world’s fastest supercomputer, with more double exponential growth to come.”
“We’ve already peeled away from classical computers, on to a totally different trajectory,” said the spokesperson.
Martinis from the Google research team added: “We’re looking forward to having them look at our data and validate our results some more.”
Regardless of Google’s claims or IBM’s counter claims, the former’s Sycamore is the first programmable and fault tolerant superconducting quantum computer that can work on versatile set of instructions for various tasks instead of being limited to a specific task.
Google has reportedly achieved this feat by turning off one faulty qubit out of the available 54 qubits on Sycamore to eliminate errors resulting from interaction with other qubits.
Appreciation for Google’s Sycamore Quantum Computer
IBM’s blog post has commended Google’s effort despite its reservations with the concept of “Quantum Supremacy”:
“Google’s experiment is an excellent demonstration of the progress in superconducting-based quantum computing, showing state-of-the-art gate fidelities on a 53-qubit device.”
“It is well known in the quantum community that we at IBM are concerned of where the term ‘quantum supremacy’ has gone,” the IBM blog states.
“A headline that includes some variation of “Quantum Supremacy Achieved” is almost irresistible to print, but it will inevitably mislead the general public.”
Future of Quantum Computing
Google has set up its Quantum research lab (aka Google AI Quantum Lab) in association with NASA and Universities Space Research Association for its further development of quantum algorithms and fabricate new quantum processors.
The lab is being run under the able-leadership of John Martinis (Chief Scientist Quantum Hardware) and Sergio Broxio (Chief Scientist Quantum computing Theory). It is situated at NASA’s Ames Research Center to support quantum systems that can accelerate computational tasks for machine intelligence.
AI and Machine Learning will be the future applications of quantum computing as these areas rely heavily on complex optimization problems like the Travelling Salesman puzzle as well as for processing huge statistical data such as sampling.
Major Challenges of Quantum Computing in Cryogenic Systems
Effective implementation of Quantum Computing algorithms is still a major challenge on today’s classical supercomputers as superposing and entangling of two or more states with 0s and 1s (while also preserving those states) is still practically impossible.
Furthermore, these qubits are reportedly vulnerable to interference from external factors such as brute-force hacking or data-hijacking as they cannot be easily encrypted as in case of classical computing with binary bits.
Some other external factors that could influence the qubits state are as follows:
Mechanical vibrations could alter the energy transfer to qubits and thereby lead to distortion of system’s quantum state. The vibrations need to be minimised and kept under 5nm to enable ultra-stable environment for preserving the quantum states of qubits.
Cryogenic environment needs to be maintained at temperature levels below 4K in order to prevent thermal excitation of the qubits and control the vacuum levels within the threshold to prevent the molecular or atomic collisions.
Low Working Distance and High Numerical Aperture (NA) Optics
A low working distance of the objective lens along with high NA optics is required to produce a narrow excitation spot for targeting individual trapped ions and offer high energy-efficiency for fluorescent readout of qubits.
The RF trapping potential of qubits or operating range of superconducting circuit depends on efficient electrical feedthrough. Specially designed low thermal heat load cryogenic ribbon cables could be used in the base panels of cryostation for generating high frequency signals with low signal loss.
Laser-frequency controlled gating operations could be affected when fluctuating magnetic fields alter the electronic energy states of the trapped-ions. So, shielding the quantum system from magnetic forces is quintessential for preserving the desired qubit states.