Quantum entanglement, one of the most interesting curiosities in physics, has fascinated scientists for decades. It's to do with a peculiar connection between particles, where the state of one particle instantly influences the state of another, even if they are far apart. Albert Einstein called it "spooky action at a distance," pointing out its seemingly paradoxical nature.

Instant sharing of information

In quantum computing, entanglement is essential for enabling qubits—the quantum version of traditional bits—to work together in ways that classical systems cannot. When qubits are entangled, their states are linked, allowing them to process and share information instantaneously. This unique property enables quantum computers to perform tasks such as parallel processing, which allows them to deal with multiple possibilities at once. Entanglement also supports error correction, which is necessary for stabilizing quantum systems and ensures secure communication by making tampering easily detectable.

Quicker than classical computers

These capabilities give quantum computers an edge in solving problems like molecular simulations, optimizing complex systems, and breaking encryption that would take classical computers an impractical amount of time to solve. Used in the appropriate way, quantum computers can perform certain tasks incredibly quickly.

... but entanglement is slow

But there's a problem. Despite their huge potential, the widespread adoption of quantum technologies has been affected by the speed at which entanglement itself can be generated and measured. Conventional methods achieve rates ranging from kilohertz (thousands of times per second) to megahertz (millions of times per second). This restricts the clock speed of quantum systems, making them slower than modern classical computers, which typically operate at gigahertz (billions of cycles per second). For quantum computing to achieve its true potential, it needs faster entanglement generation and measurement methods.

Or, rather, it used to be

A new research collaboration between NTT and the University of Tokyo may have found a way to do it and has already demonstrated a method to generate and measure entanglement over 1,000 times faster than conventional techniques.

Gigahertz range

Using an optical parametric amplifier (OPA) and advanced phase control technologies, the research team successfully achieved real-time entanglement generation at a clock speed of 60 gigahertz (60 billion times per second). It's the first time quantum entanglement has been generated and observed on a picosecond scale (trillionths of a second).

OPA devices boost light signals by transferring energy from a laser beam through a special crystal. They split the light into two new beams, amplifying the signal while conserving energy and phase relationships. NTT and the University of Tokyo used a terahertz-band OPA, a device originally developed for ultra-high-speed optical communication. They adapted the OPA to amplify and measure quantum states with exceptional precision. The researchers also developed a new phase synchronization method, allowing multiple high-speed measurement systems to work together seamlessly. This allowed them to measure entangled states in real time between two parties at unprecedented speeds.

Quicker, more powerful computing

What does it all mean? To begin with, faster entanglement generation means that quantum systems can be developed with clock speeds far exceeding those of current classical computers. Optical quantum processors operating in the gigahertz range could completely transform industries that require intense computational power. Applications could include simulating molecular interactions for drug discovery, optimizing supply chains, and improving machine learning algorithms.

Beyond computing, the new technology in development could also strengthen quantum communication networks, making data transmission more secure and efficient. It may also come to serve as the foundation for next-generation quantum networks capable of ultrafast and reliable information sharing.

The power of collaboration

Research was made possible through collaboration between a number of institutions. NTT provided expertise in fabricating OPAs, while the University of Tokyo took charge of the experimental design and analysis. Support also came from Japan's Moonshot Research and Development Program, which aims to advance quantum technology as a transformative tool for economic and industrial growth. It's a great example of how interdisciplinary efforts can push the boundaries of what quantum systems can achieve.

Quantum computers are coming

Now that slow entanglement generation is being managed, be in no doubt: more powerful and scalable quantum systems are on the way. The vision of quantum computers surpassing the capabilities of their classical forbears is no longer a distant possibility. It's an emerging reality.

NTT—Innovating the Future

Daniel O'Connor

Daniel O'Connor joined the NTT Group in 1999 when he began work as the Public Relations Manager of NTT Europe. While in London, he liaised with the local press, created the company's intranet site, wrote technical copy for industry magazines and managed exhibition stands from initial design to finished displays.

Later seconded to the headquarters of NTT Communications in Tokyo, he contributed to the company's first-ever winning of global telecoms awards and the digitalisation of internal company information exchange.

Since 2015 Daniel has created content for the Group's Global Leadership Institute, the One NTT Network and is currently working with NTT R&D teams to grow public understanding of the cutting-edge research undertaken by the NTT Group.