# What is quantum technology?

“** Nature isn’t classical, dammit, and if you want to make a simulation of nature, you’d better make it quantum mechanical**”

**R. Feynman**

The ‘first quantum revolution’, occurred about a century ago thanks to the discoveries of Planck, Einstein, Bohr, Heisenberg, Schrödinger and many more, which gave rise to quantum mechanics or the understanding of the microscopic realm. Quantum physics helped us understand the chemical interactions, periodic table and electronic wave functions that underpin the physics of electronic semiconductors. Today, there are many devices that depend critically on our understanding of quantum mechanical effects. These include the transistor, the laser, GPS, semiconductor devices and magnetic resonance imaging (MRI).

Significant progresses have been made since then and scientists and companies are now able to precisely control individual particles and their physical interactions, and to build new technologies and systems that exploit the properties of underlying quantum physics, including superposition and entanglement. This ‘second quantum revolution’ are commonly known as ‘Quantum Technologies’. These developments have led to important technical advances in several area, including quantum computing, quantum sensing, quantum communications and quantum simulation.

Many of these quantum technologies are ready to transition into commercial products, with significant short, medium, and long-term opportunities for new businesses and job creation across the whole supply chain, from engineering to theory and algorithms development to talent education, as shown in the figure.

Quantum computing has attracted the most attention among quantum tech since it holds incredible promises. While several governments and private sector entities around the world are pushing forward quantum computing innovation, the U.S and China have emerged as leaders in the field with huge investments, while Europe, with the Quantum Flagship initiative, is leading in terms of scientific publications. Nevertheless, the development of a useful quantum computer may take 10 or 20 years before we reach the goal of reliable, large-scale, error-tolerant quantum computers that can solve a wide range of useful problems.

On the other hand, other quantum technologies have already left the research labs and entered the market. Among those, Quantum Random Number Generators exploit quantum phenomena to produce random bits that form the keys used for cryptographic tasks such as encryption, authentication, signing and more.

Quside QRNGs deliver high-quality, unpredictable random numbers with measurable entropy to ensure the strongest level of security for any application.

## Frequently Asked Questions About Quantum Technology

If one could perfectly measure a property of a quantum system that has been prepared with a perfectly definite value for the said property, then there wouldn’t be any entropy (neither in our description of the system’s state nor in the outcomes of the measurement). However, in real implementations, this is impossible (or, in other words, noise is unavoidable) and therefore, albeit vanishingly small, there is always some amount of entropy.

There are different concrete instantiations of the abstract notion of entropy in quantum information theory, many of them with a clearly defined operational interpretation. In this post, we have briefly reviewed two of them: the von Neumann entropy and the quantum min-entropy.

In abstract terms, entropy is a measure of the amount of uncertainty or randomness in the state of a system.

TRNGs are based on measuring a specific (random) physical process to produce random digits. Thus, the randomness of such numbers comes from the underlying physical process, which may indeed be completely unpredictable. TRNGs are the baseline for security applications.

TRNGs are hardware components and sophisticated engineering is required to build them properly. Unfortunately, current communication systems rely on weak TRNG designs, compromising security and/or performance of the communications. There are mainly two reasons for this reliance on weak TRNG designs. First, some systems do not even have a dedicated TRNG hardware component, due to cost or design choice, thus relying on generic components in the system to produce random samples (e.g., clock interrupts from the operating system). Second, many TRNGs are designed based on physical principles that are complex and therefore produce “random-looking” dynamics (e.g., chaos), but which are, by principle, predictable and deterministic, which a sufficiently motivated attacker or a badly operated system may reveal to compromise security.

Building reliable, fast and unpredictable TRNGs is essential for the present and future of cryptography. And Quantum technologies are now being used to produce quantum-enhanced TRNGs, that is How do quantum number generators work.

About Quside’s phase-diffusion technology, Quside QRNGs are based on the phase-diffusion process in semiconductor lasers. The core element of the technology is converting microscopic quantum observables, which are delicate and hard to measure, into macroscopic dynamics that are robust and easy to capture. To do this, we modulate a semiconductor laser from below to above its threshold level or produce a stream of phase randomized optical pulses. This is called gain-switching.

Then, we use an interferometer to convert the phase fluctuations into the amplitude domain, generating a stream of amplitude-randomized optical pulses at the output (see refs [2, 3] for two examples of interferometers that we use). Finally, a fast photodiode converts the photonic signal into the electronic domain, where standard electronics are used for turning the analog signal into the digital realm.

At the heart, the unpredictability of the phase-diffusion technology traces back to the process of spontaneous emission, which occurs as a result of the interaction between the quantum vacuum field and the laser’s gain medium. Quside’s technology exploits this quantum-mechanical process to produce quantum-based random numbers at multiple Gigabits per second.

Testing randomness is a complex matter and the way it has been traditionally done is completely flawed. The question “how do you know it is random?” is a hard one to answer, and this is an area where we have been working since 2012, introducing our randomness metrology methodology in 2014 and collaborating with world-leading researchers from NIST, IQOQI and TU Delft to apply it in landmark experiments.

Our methodology defines strict quality bounds on all our devices to capture the quality of the unpredictability we produce, and the best part is that we can confidently do it in a transparent manner. This boosts trust and confidence with our customers, who do not have to rely on black boxes anymore for producing their cryptographic material.

In many traditional TRNGs, not based on quantum processes, it is extremely hard or even impossible to place rigorous quality bounds. As randomness is not emerging from a fundamentally random process.

Quantum technology is a class of technology exploiting the principles of quantum mechanics (the physics of sub-atomic particles), including quantum entanglement, quantum superposition and uncertainty principle. Today, scientists can precisely control quantum particles, which enable completely new areas of quantum technologies such as quantum computing, communication and sensing.

What can quantum technology do, the active control and manipulation of quantum effects enable new capabilities for computation, digital communication, sensor technology, and other applications.

Second generation quantum technology promise to be revolutionary and transformative holding significant commercial potential.

Quantum computing, in particular, promises to completely disrupt the way we process information and will allow us to address problems that even the most powerful classical supercomputers would never solve, from the chemistry behind pharmaceutical discoveries to major challenges in code breaking and materials science. Advances in quantum computer design, fault-tolerant algorithms, and new fabrication technologies are making this technology a real program ready to outperform classical computation by a decade or two in some applications.

Yes, it is. Today, there are many commercial devices exploiting the principles of quantum mechanics, just think of when we use GPS that makes use of atomic clocks. Several “second generation” quantum technologies have already made their way into commercial products, as QRNG devices, QKD systems or quantum gravimeters.

As an example, Quantum communication involves the generation and use of quantum states for communication protocols enabling new levels of security. Those protocols rely on Quantum Random Number Generators, to produce secret keys and QKD (Quantum Key Distribution) to distribute them.

The term Quantum technology refers to those technologies that are based on or exploit the effects of quantum mechanics, which are physical effects at the subatomic level and cannot be explained by classical physics. The first quantum revolution has set the base of many modern technologies, such as lasers, semiconductors, and GPS. The “second” generation of quantum technology are brought on by a deeper understanding of the quantum world and precision control individual particles, exploiting principles such as superposition and entanglement. This second quantum revolution includes several areas as quantum computing, quantum communication, quantum sensing and quantum simulation.

Domenico Tulli

Co-founder & CTO

Domenico** **leads the technology strategy, space initiatives and EU founded projects of Quside. With more than 15 years of experience on integrated photonics, he holds an Telecom. Engineering degree from Bologna University (2006), a Ph.D in Photonics from ICFO (2012) and a MBA from the TPMBA school (2022).

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