Breakthrough in Photonic Quantum Computing
Recently, researchers announced a new breakthrough in quantum photonics, which brings us one step closer to developing a practical quantum computer. This quantum computer will work at room temperature and have a reasonable size—one day it may even fit in your pocket!
Many companies, including Google, IBM, and various startups, rely on classical, so-called superconducting qubits. However, the main issue with superconducting qubits is integration. These classical qubits are relatively large, and you need a bulky readout interface and a cooling system.
Moreover, to make it operational, we have to cool it down to just a few milliKelvins, which is cooler than in deep space. The cryogenic systems used for cooling are bulky and consume a lot of energy. This is one of the main challenges to scaling these platforms up to high numbers of qubits and moving to smaller and more portable quantum computers.
Photonic Quantum Computers
On the other hand, there are photonic quantum computers that operate using photons, or simply light, to store and manipulate quantum information. A photon can also have two states: horizontal or vertical polarization, which can be used to represent the 0 and 1 states of a classical bit. However, the photon can also exist in a superposition of these two states, 0 and 1, at the same time. The photons are usually generated by a bulky external laser. Then, to perform operations on these qubits, researchers use mirrors and phase shifters to create entanglement between qubits, which is the key to performing quantum algorithms. When two photons are entangled, they are connected and affect one another, even if those particles are light-years apart. It’s mind-blowing just to think about it.
Photonic quantum computers have many advantages over those based on electrons. First of all, photons are highly immune to environmental noise, so it is easier to maintain their delicate quantum states. Photons do not interact much with their environment; that’s why photonic quantum computers can operate at room temperature, which is a huge plus to scaling it to a larger number of qubits and building a portable quantum computer.
Sounds cool, right? But here is the problem: to make a photonic quantum computer work, we have to be able to generate entangled pairs of photons. This entanglement is very useful for quantum computers because many qubits linked together generate exponential speedups on certain problems. Till today, to generate light and its quantum states, we had to use bulky optical equipment—huge lasers and many large beam splitters. Everything that is bulky (like classical qubits) is hard to scale.
In the new research published at Nature Photonics, researchers built the first photonic chip for quantum computing that integrates all of the required functionality into a tiny chip of a size 1-to-1 cm2. They were able to integrate all the complicated optics and filters together on a single chip. Actually, the size of a light source was shrunk by a factor of 1,000, which is amazing! This new chip can both generate photons and entangle them on a chip without all the bulky equipment. This work is a big step forward in building a more practical quantum computer of a reasonable size.
The new chip is a system-on-chip, and it combines two emerging technologies: a laser made of indium phosphide and a filter made of silicon nitride. The first section generates the light, and then it is connected to the second section, which has a bunch of microring resonators to force laser light to shuttle around. Then they filter out the noise from the light so it doesn’t interfere with quantum states. Eventually, two photons are abolished to generate a pair of entangled photons. This chip draws about 3 watts of power (which is quite a lot) and is able to produce 8000 pairs of entangled photons per second. That’s such exciting progress! Let me know what you think about that in the comment section below!
Advantages
What makes this technology so appealing is that photonics offers so many advantages over other types of quantum computing. It is definitely better scalable and more robust against noise; this already covers the main challenges we face with superconducting qubits. Also, they can be easily integrated with modern telecommunication systems through the use of optical fiber. This means we can easily scale photonic quantum computers, build them in a big cloud, and even build the quantum internet that will connect them. The internet will theoretically be much more secure and powerful than today’s version.
In general, photonics is already widely used in other applications like telecommunications, photonic computing, and sensors, which means that there is already a mature infrastructure for manufacturing photonic components. All of this makes it easier to develop and scale this technology.
Applications
Why is this research important? Photonic quantum computers have a huge potential to generate exponential speedups in science, and eventually, the goal is to make this world a better place. For example, we will be able to simulate the behavior of cells and organs with high accuracy, allowing a deeper understanding of aging and the development of treatments or drugs to slow or reverse it. It can potentially solve the problem of longevity. Also, quantum computers could help design new materials, enabling more sustainable and efficient use of resources and promoting the well-being of our planet and animals. That’s why I love technology—it is making this world a better place!
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Your piece on photonic quantum computers is a work of art, demonstrating the magical possibilities of photonic engineering in a variety of industries. This is just mesmerising in exploration of the complexities of employing photons, or light, to store and modify quantum information. It's as if we're witnessing the start of a new era, in which light becomes the foundation of the most complex computational systems.
The idea of photons existing in a superposition of states, expressing both 0 and 1, is mind-boggling. This is interesting where how researchers use mirrors and phase shifters to establish entanglement between photons, paving the way for quantum algorithms and breakthrough computations. The idea that entangled particles can effect each other regardless of distance is astounding, transcending space and time.
What genuinely distinguishes photonic quantum computers from their electronic counterparts is their resistance to ambient noise. You emphasises this advantage, emphasising how photons interact with their surroundings as little as possible. This unique property enables photonic quantum computers to run at room temperature, which is a huge step forward in terms of scalability and portability, which is ground breaking in itself.
However, as Anastasi frankly points out, creating entangled pairs of photons without the need of bulky optical equipment remains a considerable task. It's a barrier that must be overcome if photonic quantum computing's full promise and exponential speedups on complicated problems are to be realised.
Your article captured us and left us wanting more. It piques the interest and awakens a desire to explore the unexplored frontiers of photonic engineering. You present a vivid vision of a future in which light reigns supreme, revolutionising industries and opening the way for a new paradigm of computational power with each word.
Thank you. You always give me better understanding of technological concepts that are way beyond my experience. Your graphics really help me see what is going on in the processes. The photonic chip animation in this newsletter in particular helps but I still look forward to seeing how it will apply as the technology develops.