Lukin's 51-Qubit Russian-American Analog Quantum Computer

My sometime ex-colleague Mikhail Lukin has been doing some cool things inwards atomic physics in addition to the most recent ane is a 51-qubit quantum figurer of a sort. Read the story

Russian, United States of America of America Scientists Team Up to Create World's Most Advanced Quantum Computer

at the semi-official Russian Sputnik News server (or an master story inwards Russian or Google News).

You may encounter the dissimilar attitudes of the media inwards the 2 countries. While the U.S. media are obsessed alongside witch hunts against a boy of Donald Trump who may convey touched the manus of a Russian adult woman inwards the recent year, in addition to they wouldn't dare to cite a Russian quantum computation advance at Harvard, Russian media are celebrating the cooperation of Russian in addition to American scientists.



This Snap's hitting from the 1990s, "Power", is started past times a Russian proclamation that the U.S. companionship Transceptor Technologies began to hit the computers Personal Sputnik. ;-)

Think twice who is the aßhole here. Yes, Lukin is Putin's agent according to a Democratic Party's lawmaker.

Their results were summarized inwards a fresh quant-ph preprint

Probing many-body dynamics on a 51-atom quantum simulator

The authors are to a greater extent than oft than non affiliated alongside Harvard's physics department, 1.5 of them alongside MIT, 1 alongside Caltech, in addition to 0.5 of them alongside Harvard-Smithsonian. So despite Misha's ethnicity, that would in all likelihood brand the newspaper an American one. But Lukin of late co-founded the Russian Quantum Center. I suppose that the excogitation is to utilization lots of things over there.




While IBM in addition to Google compete for the largest quantum figurer alongside quantum supremacy – but their encoding of the quantum data is non quite clear – Lukin et al. are rattling transparent near the technology. They role strongly interacting atom arrays. In particular, it is rubidium-87 atoms. All of the atoms may endure either inwards the Earth solid set down \(\ket g\) or the excited solid set down \(\ket r\), the Rydberg state. Those excited states are meant to convey hydrogen-like energies multiplied past times \(Z^2\).




The Hamiltonian of their array is\[

\frac{{\mathcal H}}{\hbar} = \sum_i \frac{\Omega_i}2 \sigma^i_x - \sum_i \Delta_i n_i +\sum_{i\lt j} V_{ij}n_i n_j

\] where \(\sigma_x\) is the park Pauli \(2\times 2\) matrix inwards the footing \(\ket g,\ket r\), treated merely similar if it were "up" in addition to "down", in addition to \(n_i\) is \((1-\sigma_z)/2\) inwards the same footing – it is equal to \(\ket r\bra r\). The interaction constants \(V_{ij}\) seem constant inwards their gadget but the Rabi frequency \(\Omega_i\) may endure changed past times adjusting their Light Amplification by Stimulated Emission of Radiation intensities in addition to detunings, much similar the parameters \(\Delta_i\).

So they may in addition to they utilization manipulate the lasers to accomplish some instructions – in addition to something is happening alongside the quantum data stored inwards the enquiry "whether this atom or the adjacent ane is excited". I did facial expression Lukin to operate alongside excited in addition to unexcited atoms in addition to lasers – it's been his trace for quite some time.

The parameters are adjusted "continuously" in addition to for this reason, their figurer is a quantum computation counterpart of "analog computers" that existed some a century ago. They convey already computed some hard tasks using their quantum computer. But it's non some Shor-like algorithms that would role the quantum supremacy. They convey imitation some quantum development or computed optimization etc.

I scream upward that computers similar that could endure turned into full-blown quantum computers that run the park "purely digital" quantum algorithms. What is analog near Lukin's computer, later all? Perhaps the fact that the adjustable parameters are continuous? It looks rattling probable to me that a priori, all similar computers may suit their parameters continuously. You merely demand to suit them accurately plenty to pretend that your quantum figurer is "digital". And it would also endure helpful to brand some of the parameters \(V_{ij}\) adjustable.

There convey been many other proposals – in addition to people are working on proposals – how to shop the quantum bits. But the excited/unexcited atoms seem in addition to thus straightforward. I would endure surprised if some large companies that operate on this materials didn't get to pose Lukin's approach on steroids.

Lukin's device is said to crunch John Martinis' 49-qubit quantum figurer prepared at Google inwards some respects. Well, ane wages is that 51 is greater than 49 LOL. The Google's 49-qubit figurer is sometimes promised past times the halt of the year. IBM keeps on claiming that they're notwithstanding leaders, too.