A team of researchers from the Pritzker School of Molecular Engineering (PME) at the University of Chicago has made groundbreaking progress in the field of computing by successfully splitting phonons, the quantum particles responsible for transmitting sound. These pioneering experiments, recently published in the journal Science, open up new possibilities for the development of linear mechanical quantum computers.
Led by Prof. Andrew Cleland, the research team utilized an acoustic beamsplitter in two unprecedented experiments to demonstrate the quantum properties of phonons. While quantum mechanics dictates that quantum particles cannot be divided, the team sought to explore the consequences of attempting to split a phonon.
Operating at extremely low temperatures, the experiments employed individual surface acoustic wave phonons that travel on the surface of lithium niobate. The researchers used a beamsplitter to divide a sound beam in half, reflecting one portion while transmitting the other. This beamsplitter, similar to those used with light, revealed the quantum capabilities of phonons.
Interestingly, when a single phonon was sent through the beamsplitter, instead of dividing, it entered a quantum superposition state, simultaneously both reflected and transmitted. By capturing the phonon in two qubits, the researchers preserved this superposition state. A qubit is the fundamental unit of information in quantum computing, and the team achieved a two-qubit superposition, demonstrating that the beamsplitter generated a quantum entangled state.
In a subsequent experiment, the team replicated the Hong-Ou-Mandel effect, originally observed with photons in the 1980s. This effect demonstrated that when two identical photons were simultaneously sent into a beamsplitter from opposite directions, they consistently traveled together in one of the output directions. The team successfully reproduced this phenomenon with phonons, showcasing two-phonon interference.
The ability to achieve quantum entanglement with phonons represents a significant advancement, as phonons require the coordinated behavior of quadrillions of atoms to exhibit quantum mechanical properties. By harnessing the peculiar characteristics of the quantum realm, such as superposition and entanglement, researchers aim to solve complex problems that were previously unsolvable. While linear optical quantum computers rely on photons, a linear mechanical quantum computer that utilizes phonons could enable novel computational capabilities.
Unlike photon-based linear optical quantum computers, the UChicago platform integrates phonons directly with qubits, offering the potential for hybrid quantum computers that combine the strengths of both linear and qubit-based systems. The research team’s next objective is to develop a logic gate using phonons, a crucial component in computing.
The successful splitting of phonons and the demonstration of their quantum properties mark a significant milestone in the pursuit of linear mechanical quantum computing. With these achievements, the researchers have laid the foundation for the development of a new generation of computers that leverage the power of quantum mechanics.
Reference: “Splitting phonons: Building a platform for linear mechanical quantum computing” by H. Qiao, É. Dumur, G. Andersson, H. Yan, M.-H. Chou, J. Grebel, C. R. Conner, Y. J. Joshi, J. M. Miller, R. G. Povey, X. Wu NS A. N. Cleland, 8 June 2023, Science.
DOI: 10.1126/science.adg8715
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Frequently Asked Questions (FAQs) about linear mechanical quantum computing
What is linear mechanical quantum computing?
Linear mechanical quantum computing refers to a type of quantum computing that utilizes phonons, the quantum particles responsible for transmitting sound, as the basis for computational operations. It aims to harness the quantum properties of phonons, such as superposition and entanglement, to perform complex computations with potentially greater efficiency than classical computers.
How did the researchers split phonons?
The researchers used an acoustic beamsplitter, a device that can divide a beam of sound, to split the phonons. When a single phonon was sent through the beamsplitter, it entered a quantum superposition state, simultaneously reflected and transmitted. This splitting was achieved by capturing the phonon in two qubits, the basic units of information in quantum computing.
What is two-phonon interference?
Two-phonon interference is a phenomenon demonstrated by the research team, where two phonons, when sent simultaneously from opposite directions into a beamsplitter, exhibit interference. The interference results in the superposed outputs, indicating that both phonons are traveling in the same direction. This effect is analogous to the Hong-Ou-Mandel effect observed with photons in the 1980s.
How does this research contribute to the development of quantum computers?
This research represents a significant advancement towards the development of a new kind of quantum computer. By successfully splitting phonons and demonstrating their quantum properties, the researchers have laid the foundation for a linear mechanical quantum computer. This approach, which integrates phonons with qubits, has the potential to enable novel computational capabilities and pave the way for hybrid quantum computers that combine the strengths of different quantum computing systems.
What are the potential applications of linear mechanical quantum computing?
Linear mechanical quantum computing could have diverse applications in various fields. Quantum computers, including those based on phonons, have the potential to solve complex problems more efficiently than classical computers. The increased computational power offered by linear mechanical quantum computing could impact areas such as cryptography, optimization, materials science, drug discovery, and simulations of quantum systems.
More about linear mechanical quantum computing
- Splitting phonons: Building a platform for linear mechanical quantum computing – The published paper in the journal Science that discusses the research on splitting phonons and its implications for linear mechanical quantum computing.
- Pritzker School of Molecular Engineering – The official website of the Pritzker School of Molecular Engineering at the University of Chicago, where the research was conducted.
- Quantum Computing – Wikipedia page providing an overview of quantum computing and its principles, including the use of quantum properties like superposition and entanglement.
- Hong-Ou-Mandel effect – Detailed information on the Hong-Ou-Mandel effect, a phenomenon first demonstrated with photons and later replicated with phonons in the research discussed.
- Quantum Mechanics – An introductory article on quantum mechanics, the branch of physics that describes the behavior of quantum particles and forms the basis for quantum computing.
