Sound Waves Offer Breakthrough in Storing Quantum Information

Quantum computing promises unprecedented speed at solving complex problems to drive breakthroughs in the fields of AI, finance, logistics, material science, drug discovery, and cryptography.

But while the potential of the technology is vast, realizing this isn’t easy, as in practice, it has proven to be really difficult to make quantum computers work and utilize them to solve real-world problems.

Quantum computing is still an experimental technology, with researchers working on overcoming the obstacles to perform accurate simulations of quantum-level phenomena. One of the major problems here is storing information for a long time.

This is because while superconducting qubits possess great capabilities to process quantum information, they have rather limited coherence times.

Coherence is the ability of a quantum system to maintain the relationship between different states in a superposition. This fundamental property allows qubits to exist in a linear combination of basis states, enabling the parallelism and interference that are the core of quantum computing. 

Essential for performing quantum operations, coherence is rather fragile and can be easily lost through even small interactions with the environment.

If there is no coherence, the quantum behavior is lost by the qubit, making quantum computations meaningless. Meanwhile, decoherence is the process by which coherence is lost, and it continues to be a major challenge in building and operating quantum computers.

Now, superconducting qubits are a physical way to realize qubits, and they rely on maintaining quantum coherence to function. But of course, decoherence remains their biggest challenge.

Superconducting qubits are tiny circuits made of specific materials, which exploit quantum phenomena like superposition and entanglement to perform calculations. The materials used to make a circuit are cooled to almost absolute zero to make them superconducting, which means they can conduct electricity without resistance.

While these superconducting qubits are remarkable at fast calculations, they struggle to store information for prolonged periods.

An interface between photons and phonons, however, could allow quantum information to be stored in long-lived mechanical oscillators. A team at Caltech has done just that; they have introduced a platform that depends on electrostatic forces in nanoscale structures to attain strong coupling between a qubit and a nanomechanical oscillator.

The energy decay time (T1) is about 25 ms, which exceeds those realized in integrated superconducting circuits.

To explore the roots of decoherence as well as reduce its impact, the team used quantum operations. The usage of two-pulse dynamical decoupling sequences helped them achieve a longer coherence time (T2) of 1 ms, an extension from 64 μs.

The findings of the study show that in superconducting devices, mechanical oscillators can serve as quantum memories, with the potential to be used in quantum computing, sensing, and transduction.

How Sound Waves Store Quantum States Longer

Conventional computers like laptops and phones store information in the form of bits.

Bits are the smallest unit of digital information, which are fundamental pieces of logic that either take a single binary value of zero or one.

Quantum computers, meanwhile, can have a state that is both zero and one at the same time, which is known as superposition, and this is what’s behind quantum computing’s promise of solving problems that are not manageable for our classical computers.

A lot of existing quantum computers are based on superconducting electronic systems, where electrons flow without any resistance at extremely low temperatures. In these systems, when the quantum mechanical nature of electrons flows through resonators, they create superconducting qubits.

These qubits are great at performing the logical operations required for computing. But they aren’t really good at storing information, which is represented by mathematical descriptors of specific quantum systems. 

To boost the storage times of quantum states, engineers have been looking into building ‘quantum memories’ for superconducting qubits.

A team of scientists from Caltech has taken a hybrid route to these quantum memories. 

Electrical information was effectively converted into sound using this approach. To translate quantum information into sound waves, they used a tiny device that acts like a miniature tuning fork.

This enabled the lifetime of quantum states to extend as much as thirty times more than other techniques, laying the groundwork for scalable, practical quantum computers with the capacity to not just compute but also remember.

“Once you have a quantum state, you might not want to do anything with it immediately. You need to have a way to come back to it when you do want to do a logical operation. For that, you need a quantum memory.”

– Mohammad Mirhosseini, an assistant professor of electrical engineering and applied physics at Caltech

Supported by funding from the National Science Foundation and the Air Force Office of Scientific Research, the study was led by Caltech graduate students Alkim Bozkurt and Omid Golami and was published¹ in the journal Nature Physics.

It detailed the fabrication of a superconducting qubit on a chip, which was then connected to a tiny device termed a mechanical oscillator.

A mechanical oscillator is a system that showcases oscillatory motion. It is essentially a mini tuning fork, which, in the case of this study, consists of flexible plates. These plates are vibrated using sound waves at gigahertz (GHz) frequencies.

When the team placed an electric charge on those flexible plates, they could interact with electrical signals that were carrying quantum information, allowing for it to be transmitted into the device for storage as a “memory” and then be transmitted out or “remembered” later.

The researchers measured just how long it took for the oscillator to lose its quantum content once information entered the device. 

“It turns out that these oscillators have a lifetime about 30 times longer than the best superconducting qubits out there.”

– Mirhosseini

This method of constructing a quantum memory has various benefits over other techniques. Acoustic waves, for instance, travel far slower than electromagnetic waves, thus enabling more compact devices.

Electromagnetic (EM) waves are transverse waves of oscillating electric and magnetic fields that carry energy through space. They are produced by the acceleration of charged particles and encompass a spectrum including radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. 

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All EM travel at the speed of light in a vacuum and do not require a medium to propagate.

Meanwhile, acoustic waves are mechanical waves, like sound waves, that transmit energy through a medium like solid, liquid, or gas by causing the particles of the medium to vibrate, compress, and expand. These waves are characterized by properties such as frequency, amplitude, and wavelength. Acoustic waves encompass a range of frequencies, including infrasound and ultrasound.

Because mechanical vibrations, unlike EM waves, do not propagate in free space, the energy doesn’t leak out of the system and can be more strongly confined within a medium, allowing for extended storage times and mitigating undesirable energy exchange between nearby devices.

These benefits offer the possibility of many such tuning forks to be included in a single chip, providing a scalable way to quantum memories.

The study, according to Mirhosseini, exhibits minimal interaction between acoustic and electromagnetic waves needed to probe the value of this hybrid system for use as a memory element. 

“For this platform to be truly useful for quantum computing, you need to be able to put quantum data in the system and take it out much faster. And that means that we have to find ways of increasing the interaction rate by a factor of three to 10 beyond what our current system is capable of,” said Mirhosseini. And the team has ideas as to how to achieve that.

Quantum Hardware and Software: Path to Commercial Use

The new device created by Caltech scientists has been in the works for some time now.

A couple of years ago, in their previous work, the team showed that sound, especially phonons, which are individual particles of vibration much like how photons are, could provide an easy way to store quantum information.

At the time, Mirhosseini’s group showed the new method in the lab, where they explored phonons due to the relative convenience of building small devices that can store these mechanical waves.

The team tested devices in experiments that looked suitable for pairing with superconducting qubits, as they work at the same very high GHz frequencies.

Humans hear in the hertz to kilohertz range (up to ~20 kHz), whereas the devices operate at gigahertz (billions of cycles per second)—around 50,000× higher in frequency.

The devices tested also had long lifetimes and performed well at the low temperatures that are required to preserve quantum states with superconducting qubits.

As Mirhosseini noted at the time, other studies have looked into piezoelectrics, a special type of material, as a way to convert mechanical energy to electrical energy in quantum applications. He added:

“These materials, however, tend to cause energy loss for electrical and sound waves, and loss is a big killer in the quantum world.”

The novel technique that’s developed by the Caltech team, in contrast, does not rely on particular materials’ properties and, as such, is suitable with established microwave-based quantum devices.

Building effective storage devices with a compact size is yet another challenge for those exploring quantum applications.

This challenge is also addressed by the new method, which “enables the storage of quantum information from electrical circuits for durations two orders of magnitude longer than other compact mechanical devices,” said lead study author Bozkurt, who’s a graduate student in Mirhosseini’s group.

While Caltech’s sound-wave platform is promising, it is only one part of a much larger research effort going on all over the world across institutions. Scientists are testing diverse methods to overcome the challenges with quantum computers. 

For instance, researchers from the University of Southern California have turned to mathematics².

They are using neglectons to solve some of the problems with topological qubits. This class of theoretical particles, which are named such for how they were derived from overlooked theoretical math, could open a new pathway toward experimentally realizing universal topological quantum computers.

“My goal is to make as compelling a case as possible to other researchers that the nonsemisimple framework is not just valid but an exciting approach to better understanding quantum theory.”

– Co-author Aaron Lauda

Meanwhile, in another approach, scientists are controlling the light emitted by quantum dots, which can lead to cheaper, faster, and, of course, more practical quantum technologies.

For this, the research collaboration found a new method³ that relies on stimulated two-photon excitation, allowing quantum dots to emit photon streams in distinct polarization states without needing electronic switching hardware. When tested, the researchers were able to successfully produce excellent two-photon states while keeping remarkable single-photon properties.

“What makes this approach particularly elegant is that we have moved the complexity from expensive, loss-inducing electronic components after the single photon emission to the optical excitation stage, and it is a significant step forward in making quantum dot sources more practical for real-world applications.”

– Lead researcher, Vikas Remesh

Then there’s the team from The Grainger College of Engineering at the University of Illinois Urbana-Champaign, which has presented a high-performance modular design⁴ for superconducting quantum processors with ~99% fidelity. 

The modular architecture, unlike the restrictive monolithic designs, offers greater scalability, easier improvements, and resilience to inconsistencies.

While most efforts clearly continue to focus on the hardware part of quantum computers, a shift is now being seen towards software as people believe the technology to be “on the cusp of becoming commercially viable,” and thus needing something useful to be done with them.

In regard to that, quantum algorithms company Phasecraft raised $34 million from several backers, including the investment company linked to Danish pharmaceuticals giant Novo Nordisk (NVO -1.86%). 

Phasecraft’s algorithms, its CEO, Ashley Montanaro, believes, will be able to run “scientifically important” calculations by “next Spring,” and some commercially useful applications may be available “within the next couple of years.”

There is now a growing interest in algorithms. Recently, a researcher at Google claimed to have devised a 20-fold reduction in the scale of a quantum computer needed to run Shor’s algorithm, which can be used to crack today’s most widely used forms of encryption. 

In response, developer Hunter Beast has introduced BIP 360 in an attempt to make Bitcoin (BTC) quantum computing resistant.

Meanwhile, quantum computing company Norma validated the performance of its quantum AI algorithms for drug development using NVIDIA CUDA-Q, observing computational speeds about 73 times faster.

Investing in Quantum Computing

Many big names are conducting research in superconducting quantum computing, and that includes IBM (IBM -0.82%), Intel (INTC +1.91%), and many more. But today, we’ll look into Honeywell International (HON -0.35%), which is heavily involved in quantum computing through its majority stake in Quantinuum. 

Quantinuum, A Honeywell International (HON -0.35%) Company

Quantinuum is a quantum computing company formed in 2021 by the merger of Cambridge Quantum and Honeywell Quantum Solutions. In order to accelerate the development of fault-tolerant quantum computers, it has secured funding from investors like JPMorgan Chase.

Last year, it demonstrated the most reliable logical qubits on record. Quantinuum applied Microsoft’s breakthrough qubit-virtualization system, with error diagnostics and correction, to its ion-trap hardware to run more than 14,000 individual experiments without a single error. 

Last month, Quantinuum launched two new open source software components, including Guppy, a language hosted inside Python, which has been described by its CEO, Rajeeb Hazra, as “a paradigm shift for developers,” and an emulator called Selene, which is a “digital twin” that mimics the quantum behavior for programmers to test and debug their code.

The new full-stack platform comes in preparation for the upcoming launch of Quantinuum’s next-gen quantum computer Helios.

So, the company is pursuing advances in both quantum hardware and software with its research and commercial activities targeting AI, cybersecurity, chemical simulation, and other applications.

Through Quantinuum, Honeywell has advanced trapped-ion quantum computers, which use electromagnetically trapped ions as qubits for high-fidelity computations, to customers in various sectors, including healthcare, finance, and utilities.

The integrated operating company is mainly involved in three megatrends, which are automation, aviation, and energy transition. Meanwhile, it serves through a few key segments:

• Aerospace Technologies
• Industrial Automation
• Building Automation and Energy
• Sustainability Solutions

With a market cap of $139.36 billion, HON shares, as of writing, are trading at $218.40, down 2.83% YTD. It has an EPS (TTM) of 8.79 and a P/E (TTM) of 24.96. The dividend yield, meanwhile, is 2.06%.

As for financials, Honeywell reported sales of $10.4 billion for the second quarter of 2025. Earnings per share were $2.45, and adjusted EPS was $2.75.

During this period, the company completed a $1.3 billion Sale of PPE business, closed the $2.2 billion acquisition of Sundyne, and announced a £1.8 billion acquisition of Johnson Matthey’s Catalyst Technologies Business. The company also repurchased $1.7 billion of its shares.

CEO Vimal Kapur noted the significance of delivering “outstanding results” with both organic growth and adjusted EPS surpassing guidance despite unpredictable macroeconomics.

“With Building Automation leading the way, three out of four segments grew sales at better than 5% in the quarter, demonstrating the power of our Accelerator operating system to adapt quickly and drive growth even as business conditions change,” said Kapur while noting “promising results from our increased focus on new product innovation, which further supported the growth of our record backlog.”

Conclusion

Quantum computing can lead to significant advances in AI, healthcare, material science, cybersecurity, and other industries. But the progress of this technology depends not only on qubit performance but also on the ability to store quantum information reliably.

The Caltech platform offers a plan to achieve that. By integrating computation and memory in a single chip, the new development is moving the field closer to real-world applications.

Click here for a list of the five best quantum computing companies.

References:

1. Bozkurt, A. B., Golami, O., Yu, Y., Tian, H., & Mirhosseini, M. (2025). A mechanical quantum memory for microwave photons. Nature Physics, (advance online publication), published 13 August 2025. Received 10 January 2025; accepted 17 June 2025. https://doi.org/10.1038/s41567-025-02975-w
2. Iulianelli, F., Kim, S., Sussan, J., et al. Universal quantum computation using Ising anyons from a non-semisimple topological quantum field theory. Nature Communications, 16, 6408, published 05 August 2025. Received 13 October 2024; accepted 18 June 2025. https://doi.org/10.1038/s41467-025-61342-8
3. Karli, Y., Avila Arenas, I., Schimpf, C., et al. Passive demultiplexed two-photon state generation from a quantum dot. npj Quantum Information, 11, 139, published 11 August 2025. Received 10 April 2025; accepted 25 July 2025. https://doi.org/10.1038/s41534-025-01083-0
4. Mollenhauer, M., Irfan, A., Cao, X., et al. A high-efficiency elementary network of interchangeable superconducting qubit devices. Nature Electronics, 8, 610–619, published 27 June 2025 (issue date July 2025). Received 08 September 2024; accepted 23 May 2025. https://doi.org/10.1038/s41928-025-01404-3