The Israeli companies tackling the engineering challenge of building quantum computers are doing so using different technological approaches. Rarely competing against each other. Instead, they operate with a shared sense of “us against the world”

The quantum processor is the core of the computer, a computing unit that operates according to principles of quantum mechanics. It receives a request and produces output like a conventional computer processor; however, its basic unit of computing is a qubit.

To understand what is required of a quantum processor to be practically useful, it is important first to assess the size of the gap between the current state of the technology and the ultimate goal. While quantum computing has the potential to generate more than USD 1 trillion in value for the global economy, realizing that potential will require an extremely large-scale quantum computer, with at least one million qubits and advanced error-correction capabilities.

The largest quantum computer in existence today contains only 1,000-2,000 physical qubits, still three orders of magnitude short of the target at which a quantum computer will demonstrate genuine superiority over a conventional computer. Why are so many qubits needed? The types of problems quantum computers are expected to solve require extremely long calculations involving many sequential operations. Errors can occur at each stage of the process and accumulate throughout the computation.

Alongside the performance gap, there is also an accessibility problem. Today, quantum computers are large, expensive, and highly complex systems that are primarily accessible to governments and major technology companies. In that sense, the field resembles an earlier era of classical computing, when computer systems were centralized, extremely costly, and available only to a select few.

The Challenge: Creating Interactions Between Photons

Quantum Source has chosen a photonic approach, using photons (particles of light) as the foundation of its quantum processor. “The major advantage of photons is scalability: once you build the right building block, you can replicate it again and again and build a quantum processor as big as you want”, explains Oded Melamed, the company’s CEO and co-founder.

A longstanding challenge in photonic computing is that photons rarely interact with one another naturally. As a result, the central challenge in the photonic approach is the creation of controlled, efficient interactions between photons. In many conventional approaches, individual operations succeed only a fraction of the time and therefore requires numerous repetitions.

The company’s solution, based on research conducted at the Weizmann Institute of Science, uses atoms as intermediaries. “We transfer the quantum information from the photon to the atom, store it there, and when the next photon arrives, transfer the information to that photon”, Melamed explains. “The atoms excel at storing information and act like a kind of needle, weaving the photons that transfer information throughout the system”.

The technology is based on interactions between individual atoms and photons inside a precisely engineered physical structure known as a “cavity”. The interaction enables the generation of photons “on demand” and the creation of controlled connections between them. Instead of attempting to force photons into direct interaction – an extremely difficult task with a very low probability of success – the system uses atoms as mediators to transfer information between them, a deterministic approach that is orders of magnitude more efficient than other photonic approaches.

Quantum Source’s deterministic approach enables direct control over the process. The transition from a probabilistic to a deterministic approach alters the entire system’s........

© The Times of Israel (Blogs)