Ultrafast quantum simulator developed to solve complex materials problems

A team of researchers, headed by Professor Kenji Ohmori at the Institute for Molecular Science, National Institutes of Natural Sciences, has made groundbreaking strides in quantum simulation. They harnessed an artificial crystal comprising 30,000 atoms meticulously arranged in a cubic structure with a spacing of 0.5 microns. This crystal, cooled to near absolute zero, was manipulated using a specialized laser that pulsed for a mere 10 picoseconds. This achievement showcased their innovative “ultrafast quantum computer” concept, demonstrating its potential as a groundbreaking platform. Notably, it circumvents the formidable issue of external noise, a significant concern in quantum simulation. The “ultrafast quantum simulator” holds promise for advancing the design of functional materials and addressing societal challenges.

These remarkable findings were detailed in an online publication in Physical Review Letters.

Quantum technology, which has witnessed intense competition in recent years, encompasses quantum computers, quantum simulators, and quantum sensors. This technology leverages the wave-like properties of electrons and atoms. Given its transformative potential across various domains such as functional materials, pharmaceuticals, information security, and artificial intelligence, substantial global investments are being made in quantum technology.

A quantum simulator serves as a tool for emulating the intricate behaviors of electrons and microscopic particles in solids, mapping them onto a highly controllable model material. Its potential lies in tackling problems that would be computationally infeasible, even with the fastest supercomputers. This disruptive innovation could resolve issues like logistics, traffic congestion, and the development of superconducting and magnetic materials.

However, quantum states, generated by quantum particles like electrons and atoms, are susceptible to degradation due to external noise and laser interference, posing challenges in quantum computer development.

In 2022, Professor Kenji Ohmori’s research team at the National Institutes of Natural Sciences accomplished an ultrafast two-qubit gate, operating in a mere 6.5 nanoseconds using cold atoms. This marked a two-order-of-magnitude enhancement in the speed of the two-qubit gate compared to traditional cold-atom methods, setting the stage for an ultrafast quantum computer capable of mitigating noise effects.

If their ultrafast approach can be extended to quantum simulations, it has the potential to address the noise issue, paving the way for a highly dependable and pioneering quantum simulator.

Research results

The research team conducted ultrafast quantum simulations of magnetic materials by meticulously preparing an atomic array comprising 30,000 atoms, chilling them to temperatures approaching absolute zero, and executing precision manipulation with laser pulses lasting a mere 10 picoseconds.

Remarkably, this ultrafast quantum simulator achieved the fastest simulation of quantum entanglement, a phenomenon celebrated with the Nobel Prize in Physics the previous year. Quantum entanglement, an exclusive correlation among quantum particles, materialized within 600 picoseconds, setting a world record. The ultrafast quantum simulator leveraged the inventive “ultrafast quantum computer” strategy, adeptly sidestepping the Rydberg blockade effect with its rapid laser.

Surmounting the challenge of noise and achieving swift, precise control are the linchpins of dependable quantum simulation. The group’s achievement in realizing the world’s speediest quantum simulation surpasses conventional simulators by three orders of magnitude and outpaces noise by over 1,000 times, rendering noise effects negligible.

Quantum entanglement, an enigmatic correlation intrinsic to quantum particles like atoms and electrons constituting matter, represents a cornerstone of comprehending the quantum realm. Nonetheless, measuring it in large-scale systems and tangible materials has long been deemed exceedingly challenging.

This feat, simulating the emergence of extensive “quantum entanglement” at ultrafast intervals, is poised to foster quantum technology development. Understanding “quantum entanglement,” a pivotal resource for future quantum computers and quantum networks, in large-scale systems approaching practical use holds immense promise.

Moreover, quantum simulations of magnetic materials are poised to advance our comprehension of material properties, particularly magnetism’s origins. This will offer valuable insights for crafting next-generation devices and functional materials that unleash dramatic capabilities through quantum mechanical effects.

The experiment centered on rubidium atoms. Initially, 30,000 gaseous rubidium atoms underwent laser cooling, plummeting their temperature to less than 10 millionths of a Kelvin. Subsequently, an artificial crystal was meticulously constructed by arranging these atoms in a cubic lattice with 0.5-micron intervals, using an optical lattice.

The researchers then directed ultrashort laser pulses, flashing for a mere 10 billionths of a second, to excite electrons confined in the 5S orbitals of atoms, propelling them into colossal 35D electron orbits (Rydberg orbitals). The outcome was the observation of “quantum entanglement” formation—a distinctive correlation inherent to quantum particles—over a span of a few hundred picoseconds, fueled by potent interactions among distant atoms.

Future development and social significance of this research

The breakthrough achieved in ultrafast quantum simulations of magnetic materials through the cold-atom platform is the product of a unique scheme crafted by the same research group. Their method, enabling the manipulation of a 30,000-atom array with an ultrafast laser, has unveiled the potential of the ultrafast quantum simulator as a game-changing platform.

This innovative ultrafast quantum simulator, nurtured by the research team, is poised for future enhancements. These enhancements are expected to shed light on the fundamental properties of materials, including the mysteries of magnetism. Moreover, it will serve as a guiding compass for the design of quantum materials capable of unleashing extraordinary functions, thereby catalyzing innovation in materials research.

The simulator’s impact extends to the realm of quantum technology, offering insights into quantum entanglement, an indispensable asset for quantum computers and quantum networks. By delving into large-scale systems approaching practical use, it’s poised to contribute significantly to the development of quantum technology. Furthermore, it has the potential to evolve into a tool for tackling societal challenges like logistics, traffic congestion, and efficient power transportation—complex issues that even supercomputers struggle to address—by harnessing the power of quantum mechanical effects.

Source: National Institutes of Natural Sciences

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