New Metasurface Creates Scalable Quantum Light Source

Solving Quantum Light

Quantum computing holds many promises, from solving otherwise impossible-to-compute calculations, potentially even breaking all existing forms of encryption along the way, to creating ultra-efficient computers from an energy consumption point of view.

If quantum computers became powerful enough, they could completely revolutionize medicine through the instantaneous calculation of protein 3D configuration, material sciences, climate modeling, or even training AIs.

Most likely, communication between quantum chips and quantum computers will be done through the use of the elementary particle of light: photons.

More precisely, entangled photons, where they interact with each other through quantum effects, even when they are separated. Especially as it is now proven that we can use normal optical fibers to transmit quantum data over at least dozens of kilometers.

However, producing entangled photons has been a huge challenge, and hinders the possibility of scaling up quantum computers to a size, reliability, and cost level where they are useful.

Workarounds are being developed, for example, the production of single photons out of an imperfect photon source, through nonlinear optics and single photon teleportation. Boosting light sources’ efficiency using erbium is another potential option.

But ultimately, a lot of these solutions might be too complex to solve the problem, which is why a newly developed metamaterial could change the future of quantum computers. This nanoscale component, able to transfer into light scalable, low-decoherence quantum information, was developed by researchers at Harvard University and published in the prestigious review Science¹ under the title “Metasurface quantum graphs for generalized Hong-Ou-Mandel interference”.

Quantum Light Sources

In order to transfer data between a quantum computer's sub-components and between different quantum computers, the quantum data needs to be preserved. This is normally achieved through the creation of entangled particles, especially photons.

These entangled particles will replicate each other's state, even when separated by great distances.

So far, researchers in quantum computing have been mainly using “traditional” ways of generating entangled photons. This is either through passing the photons through waveguides on extended microchips or through bulky devices built from lenses, mirrors, and beam splitters.

The problem is that these systems are too large, complex, and difficult to produce in sufficient quantities for the method to scale up to the numbers required by a quantum network.

Another problem is “decoherence”. Greater mathematical complexity arises once the number of photons and, therefore, the number of qubits begins to increase.

Every additional photon introduces many new interference pathways, which in a conventional setup would require a rapidly growing number of beam splitters and output ports.

Quantum Metasurface

Metamaterials

Metamaterials are changing the structure of a given material, giving it different characteristics than the properties of the base materials it is made from.

This is most often achieved by creating repeating patterns of precise shape, geometry, size, orientation, etc. all at the nanoscale.

The creation of regular micro-structures in a controlled way can lead to improved performance of a material compared to its base component. This can be affected by many different properties, such as electromagnetic, acoustic, structural strength, thermal, etc.

Source: Science

This is what the Harvard researchers have created, with a new type of metasurfaces, flat devices etched with nanoscale light-manipulating patterns.

“We’re introducing a major technological advantage when it comes to solving the scalability problem.

Now we can miniaturize an entire optical setup into a single metasurface that is very stable and robust.”

Kerolos M.A. Yousef – Graduate Student at Harvard

How the Metasurface Enables Scalable Quantum Light

The mathematical complexity of many photons required for complex quantum calculations can be handled with a branch of mathematics called graph theory. Explained simply, it uses points and lines to represent connections and relationships.

Source: Science

While graph theory is used in certain types of quantum computing and quantum error correction, it has not yet been used in the context of metasurfaces, especially in their design and operation.

Graph theory made the researchers able to visually determine how photons interfere with each other and to predict their effects in experiments.

New Photon Entanglement Device

Using graph theory and commercial semiconductor manufacturing techniques, the researchers created “compact multiport interferometers”.

They used graph theory to encode both the physical design and the quantum correlations it produces into the nanostructure of the interferometers.

“It also offers fresh insight into the understanding, design, and application of metasurfaces, especially for generating and controlling quantum light. With the graph approach, in a way, metasurface design and the optical quantum state become two sides of the same coin.”

Neal Sinclair – Research at Harvard University

They then tested its performance, using superconducting nanowire detectors to measure photon behavior.

It proved that this approach provides many advantages:

• The design doesn't require intricate alignments, making the manufacturing and setup a lot easier.
• It is very resistant to perturbations, with low optical losses.
• It is simple to manufacture, making it more scalable and more cost-effective.

This work was mostly concentrated on the possible applications in quantum computing.

It could, however, also be useful for quantum sensing, or offer “lab-on-a-chip” capabilities for fundamental scientific research.

“I’m excited about this approach, because it could efficiently scale optical quantum computers and networks — which has long been their biggest challenge compared to other platforms like superconductors or atoms,”

Neal Sinclair – Research at Harvard University

Investing in Quantum Computing

Honeywell / Quantinuum

Quantinuum is the result of the merger of Honeywell Quantum Solutions and Cambridge Quantum.

Honeywell remains the company's majority shareholder (likely 52% ownership) after a fundraising round valuing it at $5B. Founder Ilyas Khan is reported to own approximately 20% of the company. Other shareholders include JSR Corporation, Mitsui, Amgen, IBM, and JP Morgan.

A potential IPO of Quantinuum in the future, potentially as a part of a larger corporate restructuring, is estimated to be worth as much as $20B and might occur between 2026 and 2027.

Quantum computing is not the central part of Honeywell's business; it is more centered around products in aerospace, automation, and specialty chemicals & materials.

Each of these domains might, however, benefit from quantum computing, especially computational chemistry and quantum cybersecurity, potentially giving Honeywell an advantage against its competitors.

The company's main model for now is the H2, a trapped-ion 56-qubit chip, with 99.895% two-qubit gate fidelity.

The next 3 generations, going up to 1000+ qubits, are already planned, with the next releases scheduled in 2025, 2027, and 2029.

Source: Quantinuum

The latest version, dubbed Apollo, would be the breakthrough that would enable countless commercial applications to be done with quantum computing.

In conclusion, through a combination of advances in hardware readiness and QEC, we have line-of-sight to Apollo by the end of the decade, a fully fault-tolerant quantum-advantaged machine. This will be a commercial tipping point: ushering in an era of scientific discovery in physics, materials, chemistry, and more.

The company has pursued high-quality computing with very few errors, rather than adding as many as possible failure-prone qubits, creating a so-called “fault-tolerant quantum computing”.

This approach is labeled by the company “Better qubits, better results”, with a similar amount of qubits achieving 100-1,000 fold more reliable results.

Source: Quantinuum

This could notably make a difference in urgently needed quantum-resistant cryptography, with defense company Thales (HO.PA -0.96%) already collaborating with Quantinuum as well as the international banks HSBC and JP Morgan.

Quantinuum also offers its proprietary quantum computational chemistry InQuanto, usable for pharmaceuticals, material sciences, chemicals, energy, and aerospace applications.

Like many other quantum computing companies, Quantinuum offers Helios, a “hardware-as-a-service”, allowing users to benefit from quantum computing without having to deal with the complexity of operating the system themselves.

Quantinuum signed in November 2024 a partnership with German Infineon, Europe’s largest semiconductor manufacturer. Infineon will bring its integrated photonics and control electronics technology to help create the next generation of trapped-ion quantum computers.

As integrated photonics are moving closer to practical use cases, it is now clear how important this partnership might be for the future of Quantinuum. At this point, it seems that the next step for the company will be to release the world's first AI-focused photonics-quantum chip.

In the coming months, Quantinuum will share results from ongoing collaborations, showcasing the groundbreaking potential of quantum-driven advancements in Generative AI.

The innovative Gen QAI capability will enhance and accelerate the use of Metallic Organic Frameworks for drug delivery, paving the way for more efficient and personalized treatment options, with details to be unveiled at the launch of Helios.

Quantinuum Announces Generative Quantum AI Breakthrough with Massive Commercial Potential

The announcement in this publication is part of a string of news related to the quick progress of the AI-quantum computing connection made at Quantinuum.

More ongoing use cases could strongly boost the future value of the company, and therefore, Honeywell’s stack in it, and the potential profit investors could make from it.

(You can also read our complete report regarding Honeywell's core business in sensors, aerospace parts, and advanced materials, besides its involvement in Quantinuum)

Latest Honeywell (HON) Stock News and Developments

Study Referenced

^{1. Kerolos M. A. Yousef, Marco D’Alessandro, Matthew Yeh, Neil Sinclair, Marko Loncar, and Federico Capasso. Metasurface quantum graphs for generalized Hong-Ou-Mandel interference. Science. 24 Jul 2025. Vol 389, Issue 6758 pp. 416-422. DOI: 10.1126/science.adw8404}