2D array of electron and nuclear spin qubits opens new frontier in quantum science

By utilizing photons and electron spin qubits to manage nuclear spins in a two-dimensional materials, researchers at Purdue University have opened a brand new frontier in quantum science and expertise, enabling functions like atomic-scale nuclear magnetic resonance spectroscopy, and to learn and write quantum info with nuclear spins in 2D supplies.

As revealed Monday (Aug. 15) in Nature Materials, the analysis crew used electron spin qubits as atomic-scale sensors, and in addition to impact the primary experimental management of nuclear spin qubits in ultrathin hexagonal boron nitride.

“This is the first work showing optical initialization and coherent control of nuclear spins in 2D materials,” mentioned corresponding creator Tongcang Li, a Purdue affiliate professor of physics and astronomy and electrical and laptop engineering, and member of the Purdue Quantum Science and Engineering Institute.

“Now we can use light to initialize nuclear spins and with that control, we can write and read quantum information with nuclear spins in 2D materials. This method can have many different applications in quantum memory, quantum sensing, and quantum simulation.”

Quantum expertise is dependent upon the qubit, which is the quantum model of a classical laptop bit. It is usually constructed with an atom, subatomic particle, or photon as an alternative of a silicon transistor. In an electron or nuclear spin qubit, the acquainted binary “0” or “1” state of a classical laptop bit is represented by spin, a property that’s loosely analogous to magnetic polarity—that means the spin is delicate to an electromagnetic area. To carry out any process, the spin should first be managed and coherent, or sturdy.

The spin qubit can then be used as a sensor, probing, for instance, the construction of a protein, or the temperature of a goal with nanoscale decision. Electrons trapped within the defects of 3D diamond crystals have produced imaging and sensing decision within the 10–100 nanometer vary.

But qubits embedded in single-layer, or 2D supplies, can get nearer to a goal pattern, providing even larger decision and stronger sign. Paving the best way to that objective, the primary electron spin qubit in hexagonal boron nitride, which might exist in a single layer, was in-built 2019 by eradicating a boron atom from the lattice of atoms and trapping an electron instead. So-called boron emptiness electron spin qubits additionally provided a tantalizing path to controlling the nuclear spin of the nitrogen atoms surrounding every electron spin qubit within the lattice.

In this work, Li and his crew established an interface between photons and nuclear spins in ultrathin hexagonal boron nitrides.

The nuclear spins will be optically initialized—set to a recognized spin—through the encompassing electron spin qubits. Once initialized, a radio frequency can be utilized to alter the nuclear spin qubit, basically “writing” info, or to measure modifications within the nuclear spin qubits, or “read” info. Their methodology harnesses three nitrogen nuclei at a time, with greater than 30 occasions longer coherence occasions than these of electron qubits at room temperature. And the 2D materials will be layered instantly onto one other materials, making a built-in sensor.

“A 2D nuclear spin lattice will be suitable for large-scale quantum simulation,” Li mentioned. “It can work at higher temperatures than superconducting qubits.”

To management a nuclear spin qubit, researchers started by eradicating a boron atom from the lattice and changing it with an electron. The electron now sits within the middle of three nitrogen atoms. At this level, every nitrogen nucleus is in a random spin state, which can be -1, 0, or +1.

Next, the electron is pumped to a spin-state of 0 with laser gentle, which has a negligible impact on the spin of the nitrogen nucleus.

Finally, a hyperfine interplay between the excited electron and the three surrounding nitrogen nuclei forces a change within the spin of the nucleus. When the cycle is repeated a number of occasions, the spin of the nucleus reaches the +1 state, the place it stays no matter repeated interactions. With all three nuclei set to the +1 state, they can be utilized as a trio of qubits.

At Purdue, Li was joined by Xingyu Gao, Sumukh Vaidya, Peng Ju, Boyang Jiang, Zhujing Xu, Andres E. Llacsahuanga Allcca, Kunhong Shen, Sunil A. Bhave, and Yong P. Chen, in addition to collaborators Kejun Li and Yuan Ping on the University of California, Santa Cruz, and Takashi Taniguchi and Kenji Watanabe on the National Institute for Materials Science in Japan.

“Nuclear spin polarization and control in hexagonal boron nitride” is revealed in Nature Materials.