Now for something completely different to kick off 2022. A group of scientists have reported entangling a tough tiny critter – the Tardigrade ⟦i⟧ – with two superconducting qubits. Tardigrades (aka water bears), it turns out, are not merely hardy but also nearly immune to inhospitable environments such as outer space…and, of course, dilution refrigerators housing quantum computing processors.
There’s a good piece recounting the effort posted on IEEE Spectrum. As noted by Philip E. Ross in his IEEE Spectrum article, “Actually entangling a living creature would be quite a feat for the physicists, perhaps more so for the biochemists. Complex chemical systems don’t normally stand still for inspection.” Indeed. Not everyone is buying it, but first, what is the claim?
Here’s a brief excerpt from the article:
“Now a group of scientists say they’ve entangled a tardigrade, commonly called a water bear, a cute critter that’s just barely visible to the naked eye.
“The 11 researchers have published their work on 15 December in the online preprint server arXiv, which is not peer-reviewed. Among them are Rainer Dumke of the Center for Quantum Technologies, in Singapore, and Tomasz Paterek of the University of Gdansk, in Poland, who in 2019 were honored, so to speak, with an IgNobel Prize for their work on magnetized cockroaches (the results of which bear on methods by which animals navigate).
“Let the record show that at least one winner of the IgNobel, Andre Geim, went on to win an actual Nobel. He got the IgNobel one for levitating a frog, the real Nobel for discovering graphene.” (A sketch of the experiment—including a photo of the revived tardigrade on the system’s qubit is shown below.)
As explained in the article, “Larger objects have been so entangled, but those objects were inanimate matter. This is a bigger claim—and one that’s harder to nail down.”
Here’s an excerpted quote from one of the authors, “We start with a superconducting qubit at energy state 0, comparable to an atom in the ground state; there’s no oscillation—nothing is happening,” Dumke says. “We can use microwaves to supply exactly the right amount of energy for the right amount of time to raise this to level 1; this is like the second orbital in an atom. It is now oscillating.
“Or, and this is the important point, we can add exactly that much energy but supply it for just half the time to raise the system to a quantum state of ½, which is the superposition state. In this state, it is at the same time oscillating and not oscillating. You can do extensive testing to measure all three states.”
That whole thing seems a stretch, and as noted by Ross, a few skeptics have weighed in, but apparently quantum theory allows such an entanglement.
Link to IEEE Spectrum article (Schrödinger’s Tardigrade Claim Incites Pushback), https://spectrum.ieee.org/schrodingers-tardigrade
⟦i⟧ Tardigrades (/ˈtɑːrdɪɡreɪd/), known colloquially as water bears or moss piglets, [are a phylum of eight-legged segmented micro-animals. They were first described by the German zoologist Johann August Ephraim Goeze in 1773, who called them kleiner Wasserbär (“little water bear”). In 1777, the Italian biologist Lazzaro Spallanzani named them Tardigrada /tɑːrˈdɪɡrədə/, which means “slow steppers”.
They have been found everywhere in Earth’s biosphere, from mountaintops to the deep sea and mud volcanoes, and from tropical rainforests to the Antarctic. Tardigrades are among the most resilient animals known, with individual species able to survive extreme conditions — such as exposure to extreme temperatures, extreme pressures (both high and low), air deprivation, radiation, dehydration, and starvation — that would quickly kill most other known forms of life. Tardigrades have survived exposure to outer space. There are about 1,300 known species in the phylum Tardigrada, a part of the superphylum Ecdysozoa consisting of animals that grow by ecdysis such as arthropods and nematodes.