Weird Quantum Material Concept

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

Quantum science has the potential to revolutionize fashionable expertise with extra environment friendly computer systems, communication, and sensing units. However challenges stay in reaching these technological objectives, particularly relating to successfully transferring data in quantum techniques.

An everyday laptop consists of billions of transistors, referred to as bits. Quantum computer systems, then again, are based mostly on quantum bits, often known as qubits, which will be produced from a single electron.

In contrast to unusual transistors, which will be both “0” (off) or “1” (on), qubits will be each “0” and “1” on the similar 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 nice potential of quantum computer systems. Similar to unusual computer systems, nonetheless, quantum computer systems want a method to switch quantum data between distant qubits—and that presents a serious experimental problem.

Quantum Processor Semiconductor Chip

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

In a sequence of papers printed 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 bettering 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 data between qubits, referred to as adiabatic quantum state switch (AQT), for the primary time with electron-spin qubits. In contrast to most strategies of transferring data 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’re driving your automobile and wish to park it. In case you don’t hit your brakes on the correct time, the automobile gained’t be the place you need it, with potential detrimental penalties. On this sense, the management pulses—the fuel and brake pedals—to the automobile have to be tuned rigorously. AQT is totally different in that it doesn’t actually matter how lengthy you press the pedals or how arduous you press them: the automobile will at all times find yourself in the suitable spot. Consequently, 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 fundamental ideas of quantum physics wherein 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 outstanding properties. That is the longest chain over which a spin state has ever been transferred, tying the document set by the researchers in a earlier 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 a wierd state of matter

In a second paper,[2] the researchers demonstrated one other strategy of transferring data between qubits, utilizing an unique state of matter referred to as time crystals. A time crystal is a wierd state of matter wherein 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 like the oscillating time crystal.

By implementing a sequence of electric-field pulses on electrons, the researchers have been in a position to create a state just 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 exhibiting how unusual and unique states of matter, like time crystals, can doubtlessly by used for quantum data processing functions, similar to transferring data between qubits,” Nichol says. “We additionally theoretically present how this state of affairs can implement different single- and multi-qubit operations that could possibly be used to enhance the efficiency of quantum computer systems.”

Each AQT and time crystals, whereas totally different, could possibly 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 data to be despatched from one place to a different, which is without doubt one of the major challenges in setting up 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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