Rigetti introduces a third energy state to its qubits, thus turning them into qutrits

(TechRadar) Rigetti has announced it is exploring experimental new hardware configurations that could improve the performance of its quantum processors.
As explained in a blog post, the firm has introduced a third energy state to its qubits, thus turning them into qutrits. According to Rigetti, doing so allows for significantly more information to be manipulated, while also decreasing readout errors by up to 60%.
“Accessing the third state in our processors is useful for researchers exploring the cutting edge of quantum computing, quantum physics and those interested in traditional qubit-based algorithms alike,” the company explained.
A quantum bit (or qubit) is the smallest unit of quantum information, an analogue to the binary bit of classical computing. However, unlike the traditional bit, a qubit can adopt a value of one, zero or anything in between by virtue of a phenomenon known as superposition.
“Qubits are the basic building block of a quantum processor, and are so named because they represent a continuum of complex superpositions of two basic quantum states,” explains Alex Hill, Senior Quantum Systems Engineer at Rigetti.
“The power of qubits comes in part from their ability to encode significantly more information than a classical bit – an infinite set of states between 0 and 1.”
Rigetti contends that the addition of a third state to qubits, creating a three-level quantum system based on qutrits, represents another path to improving the performance of quantum machines.
In future, it might even be possible to push towards qubits with an even larger number of states, says Rigetti. However, because an ever-smaller amount of energy separates states beyond zero and one, noise and control issues become increasingly difficult to surmount.