Together with the diamond giant, Amazon is revolutionizing the quantum network

Amazon is partnering with a division of the giant De Beers (De Beers) Group to grow man-made diamonds (diamonds) and betting: these custom diamonds promise to revolutionize computer networks.

Specifically, De Beers' Elementsix division will work with Amazon Web Services' Quantum Networks on the project to find the next generation of ways to securely transmit data over long distances: quantum networks, which use subatomic matter to transmit data in ways that go beyond today's fiber-optic systems. Diamond, in turn, will be part of a component that will allow data to be transmitted farther without interruption.

Traditional signal repeaters cannot handle this form of information - quantum bits. Diamond has optical and quantum properties that make it uniquely promising for several key areas of focus for AWS, including semiconductors, quantum networking and quantum communications applications, among other important uses (AWS is a cloud computing service provider that accounts for most of Amazon's profits).

"We want to build these networks for AWS," says Antia Lamas-Linares, head of the Quantum Networking Center. She estimates that the technology will be operational in "years, not decades.

For Element Six, they also hope to produce up to 2 million diamond components a year at their new facility in Oregon through "plasma enhanced chemical vapor deposition (PECSV) technology": industrial diamond is prized for its hardness and ability to be used as a lens.

Amazon hopes that PECSV diamonds will eventually help connect the many quantum computers around the world and create an extensive network capable of providing exponentially superior computing power.

Quantum networks use the properties of entanglement and superposition to securely distribute quantum information among network end users.

These networks consist of two types of nodes: backbone nodes and end-user nodes, and they each rely on different types of technology as well.

End-user nodes can use traditional telecommunication resources, such as lasers and detectors, to communicate with the backbone nodes; on the other hand, the backbone nodes will need a new type of infrastructure: quantum repeaters.

These repeaters function similarly to amplifiers in classical communication networks by correcting the losses and infidelities that occur when quantum information propagates over long distances, and are able to do so without destroying the quantum state of the light passing through the network.

This makes it possible to correct the (unavoidable) scattering of individual photons as they pass through telecommunication fibers. These repeaters thus make it possible to propagate quantum information without fear of photon loss. Quantum repeaters will serve as the backbone of the future quantum Internet and will enable secure, private communication - which is why, it is the focus of research at the AWS Quantum Network Center.

Solid defects are a widely used class of quantum bits that consist of defects formed by one or more atoms within an otherwise homogeneous crystalline material.

Depending on the type of atom and material used, quantum bits are defined by the electronic or magnetic state of the defective atom. Defective quantum bits are naturally present in many materials and can often be created by targeted, artificial implantation of defective atoms into the host material. Although there are so many materials capable of hosting defective quantum bits, finding material-defects with any particular combination of properties remains a challenging task.

Diamond is one of nature's most remarkable materials. Formed from a lattice of carbon atoms, diamond is the hardest natural material in the world, has the widest optical transmission, and is the best natural conductor of heat. It is stable in environments ranging from the deepest, coldest vacuums to extremely high pressures and temperatures - and can even be safely incorporated into living organisms.

Natural diamonds form deep within the Earth as a result of tectonic pressures more than 100 kilometers below the Earth's surface. As a result of the environment in which they grow, these diamonds are diverse and unique. Although more pure than other natural crystals, diamonds contain many different impurities from the environment during the long, slow growth process. These impurities give diamonds a wide range of colors: from deep blue to bright pink.

In some cases, the defects in diamonds do not just make them unique and beautiful: they can also serve as special quantum bits for quantum networking applications.

Diamond has many different defects, but two types of diamond-defect quantum bits have emerged as prime candidates for communication applications: nitrogen vacancy centers (NV) and silicon vacancy centers (SiV). Both nitrogen vacancy centers and silicon vacancy centers are formed by removing two adjacent carbon atoms from the diamond lattice and replacing them with a nitrogen or silicon atom, respectively.

These diagrams of NV (left) and SiV (right) show their atomic configurations within the diamond lattice. In each case, the carbon atom (silver) is replaced by a vacancy (white with black outline) and a defective atom (nitrogen in brown, silicon in gold).

The atomic defects embedded in diamond can change the way it interacts with light. Here, sixth element high-purity PECVD-grown diamonds are embedded in SiV (top right) and NV (bottom right) and annealed. When illuminated with green light, regions of pure diamond (left) do not emit light, while regions with defects produce red light of varying intensity.

The quantum repeater operates by transferring the information encoded on the photon to a fixed memory quantum bit where the information can be stored and corrected. Defective quantum bits, such as color centers, are good candidates for this operation: since they naturally have an effective interface with light (the source of their color) and have access to a long-term "spin" memory: this spin can be thought of as a tiny magnet contained within each electron, proton and neutron in the material. This spin can be accessed by placing a quantum bit in a magnetic field and orienting the spin in the direction of the field. The memory is then defined by whether the spin is oriented along the direction of the magnetic field or in the opposite direction, which corresponds to a 1 or 0 bit, respectively.

When light bounces off a color center, it can flip this spin quantum bit, making possible the transfer of information between the light and the spin memory, which is known as the spin-photon interface. Color centers with this property (such as NV and SiV) are useful candidates for quantum repeaters.

Other color centers such as NV and SiV differ in that they are housed in diamond, which is compatible with a variety of semiconductor processes and is chemically inert, stable in many different environments.

This means that these quantum bits can be placed inside nanoscale devices designed for specific applications. For example, NVs are often placed at the tip of a microscope scanning probe or at the center of a hemispherical lens or pillar used to efficiently collect light. Less environmentally sensitive SiVs can be placed within smaller structures: they are typically used in waveguides and photonic crystal cavities that are just over 100 nm wide.

Diamond pillars used to enhance color-centered light collection

Photonic crystal devices made of diamond to ensure deterministic interaction between color centers and light

Using synthetic diamond in the sixth element, these features have been exploited by teams of scientists at Harvard and MIT to enable memory-enhanced quantum communication, a benchmark that means NV will enable communication over longer distances than would be possible without a repeater.

In natural diamond, the extra number of defective atoms reduces the coherence, optical and spin properties of color centers like NV, SiV.

Fortunately, the advent of the synthetic diamond market has made it possible to reduce these additional defects. Advances in plasma-enhanced chemical vapor deposition (PECVD) over the past 20 years have enabled the growth of individual diamonds with sufficient purity and order for use in quantum applications.

PECVD growth allows the formation of diamonds hundreds or thousands of times purer than "Regent diamonds" (the famous pure natural diamonds on display at the Louvre): in the best PECVD diamonds, less than one millionth of an atom is an impurity, compared to one thousandth of an impurity in most natural diamonds.

What's more, the global CVD lab-grown diamond market is expected to grow at a CAGR of 7.1% from 2022 to 2027.

Continued investment in PECVD diamond technology will be key to making it available for quantum applications. Improved control over the types of defects and materials created during diamond growth, expansion of the different forms of diamond that can be mass-produced, and reduction in their manufacturing costs will be critical to the growth of this field.

About Element Six:

With over 70 years of technical expertise in developing growth technologies and application knowledge for synthetic diamonds, Element Six has pioneered diamond solutions in many disruptive areas, including oil and gas exploration, water treatment, advanced thermal management for high-performance semiconductor devices, and optical applications for fusion energy and EUV lithography.

Through collaboration with leading academic partners in the U.S. and Europe, Element Six has pioneered the demonstration of synthetic diamonds that can be produced with properties for quantum applications.

References:

[1]https://www.e6.com/

[2]https://aws.amazon.com/cn/blogs/quantum-computing/perfect-imperfections-how-aws-is-innovating-on-diamond-materials-for-quantum-communication-with-element-six/

[3]https://www.bloomberg.com/news/articles/2023-04-05/amazon-looks-to-grow-diamonds-in-bid-to-boost-computer-networks?srnd=technology-vp&sref=TBDibEcD&leadSource=uverify%20wall

[4]https://analyticsindiamag.com/diamonds-in-the-quantum-sky/

[5]https://arxiv.org/pdf/1909.01323.pdf

[6]CVD Lab Grown Diamonds Market, Industry Size Forecast (marketsandmarkets.com)