While we are still trying to fully appreciate the implications of the qubit, Quantum Computing has a new kid on the block
As the world is all ablaze with the excitement of superfast Quantum Computers fed by the elusive qubit, we already have the next big thing lined up. A combined team of physicists and data scientists at Berkeley has successfully achieved dissemination of quantum information through – hold your breath – “qutrits”. Just as its name suggests, qutrits are a step ahead on qubits. Because, while qubits relied on the unusual quantum behaviour of existing in two separate states at the same time, qutrits can represent three separate states simultaneously. Yes, the “trit” is exactly one ahead of the “bit”.
The ground-breaking work has demonstrated that qutrit scan serve as information-storing quantum units – just like qubits do. And they are on their way towards developing a quantum information processor based upon qutrits. The day after tomorrow is here!
Out of the Black Hole
Intriguingly, the work on qutrits is inspired by the perennial riddle of theoretical physicists: What happens to information when it enters a black hole? We all know – however vaguely – that matter and light cannot escape the vortex of a black hole. But no one was quite sure what happened to information in there. The legendary Stephen Hawking had established that black holes emit radiation, and that can pass on some information about the insides of a black hole. And this information can be reconstructed through the phenomenon of quantum entanglement by which a pair of particles can remain correlated even when separated by large distances. And, under such a condition, the state of one particle can let us infer the state of its entangled partner.
Most efforts in quantum computing seek to tap into this phenomenon by encoding information as entangled quantum bits – or qubits. Like bits in traditional computing, a qubit too can be either zero or one in value. However, displaying its quantum parentage, a qubit can also exist in a superposition state that is both one and zero at the same time. It’s like a flipping a coin that can result in either a head or a tail – as well as the strange existence of both head and tail at the same time. As a result, each qubit added to a quantum computer doubles its computing power.
Qutrits take the game a notch higher because they represent quantum units with three or more states. They can have a value of zero, one, or two, holding all of these states in superposition at the same time. That would be like a coin offering the possibilities of head, tail, or landing on its thin edge.
From Theory to Practice
The Berkeley team set out to replicate the type of rapid quantum information smearing, or scrambling, in an experiment that used tiny devices called nonlinear harmonic oscillators as qutrits. These nonlinear harmonic oscillators are essentially sub-micron-sized weights on springs that can be driven at several distinct frequencies when subjected to microwave pulses. A crucial bit of the experiment was to preserve the coherence, or orderly pattern, of the signal from oscillators for long enough to confirm successful quantum scrambling via the teleportation of a qutrit.
A common problem in making these oscillators work as qutrits, though, is that their quantum nature tends to break down very quickly via a mechanism called decoherence. As a result, it is difficult to distinguish whether the information scrambling is truly quantum or is due to this decoherence or other interference.
However, these are early days. And as we go on reporting stunning developments around qubit-driven quantum computing – we are sure to hear more about the qutrit in the coming days.
Shall definitely keep you posted!