By now the sheer repetition of the term qubit has made it seem comprehensible and quantum computing not so strange. Brace yourself. Here comes the ‘qudit’ – another form of quantum information but one that is able to assume very many values at once.
“Instead of creating quantum computers based on qubits that can each adopt only two possible options, scientists have now developed a microchip that can generate “qudits” that can each assume 10 or more states, potentially opening up a new way to creating incredibly powerful quantum computers, a new study finds,” writes Charles Choi for the IEEE Spectrum.
Choi’s article, ‘Qudits: The Real Future of Quantum Computing?’ was posted last Friday and briefly examines work published at the same time in Nature, ‘On-chip generation of high-dimensional entangled quantum states and their coherent control,’ suggesting a way to create these multi-dimensional qudits.
Here’s brief excerpt from the IEEE Spectrum article:
“Now scientists have for the first time created a microchip that can generate two entangled qudits each with 10 states, for 100 dimensions total, more than what six entangled qubits could generate. “We have now achieved the compact and easy generation of high-dimensional quantum states,” says study co-lead author Michael Kues, a quantum optics researcher at Canada’s National Institute of Scientific Research, or INRS, its French acronym, in Varennes, Quebec.
“The researchers developed a photonic chip fabricated using techniques similar to ones used for integrated circuits. A laser fires pulses of light into a micro-ring resonator, a 270-micrometer-diameter circle etched onto silica glass, which in turn emits entangled pairs of photons. Each photon is in a superposition of 10 possible wavelengths or colors.
“For example, a high-dimensional photon can be red and yellow and green and blue, although the photons used here were in the infrared wavelength range,” Kues says. Specifically, one photon from each pair spanned wavelengths from 1534 to 1550 nanometers, while the other spanned from 1550 to 1566 nanometers.”
So just when your head stopped spinning at the sound of the word qubit, along comes the qudit. In fairness, the IEEE article points out scientists have long known about the possibility of using qudits and notes, “A quantum computer with 300 qubits could perform more calculations in an instant than there are atoms in the known universe, solving certain problems much faster than classical computers. In principle, a quantum computer with two 32-state qudits would be able to perform as many operations as 10 qubits while skipping the challenges inherent with working with 10 qubits together.”
The feature image is of the microchip fabricated by the researchers. Below is a diagram (Nature) of the work.
Link to IEEE Spectrum article: http://spectrum.ieee.org/tech-talk/computing/hardware/qudits-the-real-future-of-quantum-computing
Link to Nature paper: https://www.nature.com/articles/nature22986.epdf?referrer_access_token=m2Cde8lf2Zh2R9vqdRitfdRgN0jAjWel9jnR3ZoTv0PJityhJkSWpq1THf-VSsArUhH5B2sAknySsan793cm3_eBBo9MOlyHeYxjGaqZnurhzcH7meLV3MMg5Q5-D4vlMlU-NCaRIE4XBnNREmU0z1WU8YYGcro3-m56ZnOv-djeJfdioz8743j4LAE5I8vkMm6oc8W8_hmdFSbxIjbVWNw4YvBWh0_Ct8hYflCuOY38KpBEFFTmoncxMDjN8a7vpt_r52ScoN43wj4CEhpr7A%3D%3D&tracking_referrer=spectrum.ieee.org