Weird Quantum Material Concept

Exploiting a Unusual State of Matter: Researchers Confront Main Hurdle in Quantum Computing

Weird Quantum Material Concept

In a collection of papers, Rochester researchers report main strides in enhancing the switch of data in quantum techniques.

Quantum science has the potential to revolutionize trendy know-how with extra environment friendly computer systems, communication, and sensing units. However challenges stay in attaining these technological objectives, particularly in terms of successfully transferring info in quantum techniques.

An everyday pc consists of billions of transistors, known as bits. Quantum computer systems, then again, are primarily based on quantum bits, also called qubits, which may be constituted of a single electron.

In contrast to bizarre transistors, which may be both “0” (off) or “1” (on), qubits may be each “0” and “1” on the identical time. The power of particular person qubits to occupy these so-called superposition states, the place they’re in a number of states concurrently, underlies the good potential of quantum computer systems. Similar to bizarre computer systems, nonetheless, quantum computer systems want a method to switch quantum info between distant qubits—and that presents a serious experimental problem.

Quantum Processor Semiconductor Chip

A quantum processor semiconductor chip is proven linked to a circuit board. Credit score: College of Rochester photograph / J. Adam Fenster

In a collection of papers revealed in Nature Communications, researchers on the College of Rochester, together with John Nichol, an assistant professor of physics and astronomy, and graduate college students Yadav Kandel and Haifeng Qiao, the lead authors of the papers, report main strides in enhancing quantum computing by enhancing the switch of data between electrons in quantum techniques.

Using a brand new route

In one paper,[1] the researchers demonstrated a route of transferring info between qubits, known as adiabatic quantum state switch (AQT), for the primary time with electron-spin qubits. In contrast to most strategies of transferring info between qubits, which depend on rigorously tuned electrical or magnetic-field pulses, AQT isn’t as affected by pulse errors and noise.

To ascertain how AQT works, think about you might be driving your automobile and wish to park it. Should you don’t hit your brakes on the correct time, the automobile gained’t be the place you need it, with potential destructive penalties. On this sense, the management pulses—the gasoline and brake pedals—to the automobile have to be tuned rigorously. AQT is completely different in that it doesn’t actually matter how lengthy you press the pedals or how arduous you press them: the automobile will all the time find yourself in the proper spot. Because of this, AQT has the potential to enhance the switch of data between qubits, which is crucial for quantum networking and error correction.

The researchers demonstrated AQT’s effectiveness by exploiting entanglement—one of many primary ideas of quantum physics by which the properties of 1 particle have an effect on the properties of one other, even when the particles are separated by a big distance. The researchers have been in a position to make use of AQT to switch one electron’s quantum spin state throughout a series of 4 electrons in semiconductor quantum dots—tiny, nanoscale semiconductors with exceptional properties. That is the longest chain over which a spin state has ever been transferred, tying the report set by the researchers in a previous Nature paper.

“As a result of AQT is strong in opposition to pulse errors and noise, and due to its main potential functions in quantum computing, this demonstration is a key milestone for quantum computing with spin qubits,” Nichol says.

Exploiting an odd state of matter

In a second paper,[2] the researchers demonstrated one other strategy of transferring info between qubits, utilizing an unique state of matter known as time crystals. A time crystal is an odd state of matter by which interactions between the particles that make up the crystal can stabilize oscillations of the system in time indefinitely. Think about a clock that retains ticking without end; the pendulum of the clock oscillates in time, very similar to the oscillating time crystal.

By implementing a collection of electric-field pulses on electrons, the researchers have been capable of create a state much like a time crystal. They discovered that they may then exploit this state to enhance the switch of an electron’s spin state in a series of semiconductor quantum dots.

“Our work takes the primary steps towards displaying how unusual and unique states of matter, like time crystals, can probably by used for quantum info processing functions, akin to transferring info between qubits,” Nichol says. “We additionally theoretically present how this state of affairs can implement different single- and multi-qubit operations that may very well be used to enhance the efficiency of quantum computer systems.”

Each AQT and time crystals, whereas completely different, may very well be used concurrently with quantum computing techniques to enhance efficiency.

“These two outcomes illustrate the unusual and attention-grabbing ways in which quantum physics permits for info to be despatched from one place to a different, which is likely one of the essential challenges in establishing viable quantum computer systems and networks,” Nichol says.


  1. “Adiabatic quantum state switch in a semiconductor quantum-dot spin chain” by Yadav P. Kandel, Haifeng Qiao, Saeed Fallahi, Geoffrey C. Gardner, Michael J. Manfra and John M. Nichol, 12 April 2021, Nature Communications.
    DOI: 10.1038/s41467-021-22416-5
  2. “Floquet-enhanced spin swaps” by Haifeng Qiao, Yadav P. Kandel, John S. Van Dyke, Saeed Fallahi, Geoffrey C. Gardner, Michael J. Manfra, Edwin Barnes and John M. Nichol, 6 April 2021, Nature Communications.
    DOI: 10.1038/s41467-021-22415-6

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