Did Tardigrades Meet the Quantum World? Or Was it Just a (Micro) Hoax?
In December 2021, news spread rapidly that a tardigrade, a creature that can survive in extreme environments – such as the vacuum of space, extreme cold, and exposure to UV radiation – had been quantum entangled. Quantum entanglement is a phenomenon in which the quantum states of two or more objects are described in reference to each other, even though the individual objects may be separated by vast distances due to a previous action undertaken [1]. In essence, this creates a domino effect between the objects since the actions of one particle will affect the actions of its entangled counterpart. Despite getting an enthusiastic response from the general press, this claim has been met with lots of speculation from scientists, since the research has not been formally published or peer-reviewed and arguably doesn’t present any findings of scientific value [2].
Figure 1 – A tardigrade seen under a microscope. Credit: Frank Fox, CC-BY-SA-3.0-DE, via Wikimedia Commons.
Tardigrades, which are also referred to as ‘water bears’, are known for their tolerance to extreme environments in pressure, temperature and even radiation (Fig. 1). Their tolerance can be attributed to their ability to enter anhydrobiosis [3]. Anhydrobiosis occurs when the tardigrade stops its metabolism and lives in a dehydrated state in which >99% of its body water is removed [4]. The tardigrade's tissues will return to their normal state once water is available again [4]. Quantum entanglement normally connects particles like protons and electrons, so could multicellular creatures like the tardigrade be entangled in the same way particles can?
Figure 2 – Sketch of the tardigrade-qubit hybrid paired with the other qubit. This pairing allowed for the qubits to become entangled. Reprinted from Ref [5].
K. S. Lee et al. investigated this by placing tardigrades in a state of quantum entanglement with a pair of qubits, the quantum counterpart to regular computational bits [5]. This was achieved by freezing the tardigrades to a fraction of a degree above absolute zero (-273.15℃), a temperature that tardigrades have been confirmed to survive at [5]. Each frozen tardigrade was then placed between two capacitor plates of a superconductor circuit, making the tardigrades an integral part of the capacitor. When cooled, the capacitor plates can exist in a superposition of states – a qubit. By doing this, the effect of the tardigrade on the qubit’s properties could be measured. When the tardigrades came into contact with the qubit, the qubit’s resonant frequency (the natural frequency where it is easiest to get an object to vibrate) was changed. The tardigrade-qubit hybrid was then paired with a second circuit which formed another qubit, so that the two qubits became entangled (Fig. 2). The proof that the tardigrade was also entangled stemmed from the observation that the frequency of the qubits and the tardigrade changed at the same time, which the researchers believed resembled a three-part entangled system [5].
However, some scientists remain sceptical about these findings. Douglas Nateslon, Department Chair of Physics and Astronomy at Rice University in Texas, explained on his blog that the tardigrade was not entangled with a qubit in “any meaningful sense” [6]. He explained that the tardigrade acted as a dielectric – an electrical insulator that can be polarised by an applied electric field – which caused the resonant frequency of the qubit that it sat on to shift [6]. Ben Brubaker, a former physicist and a scientific writer, expressed a similar sentiment. He stated that the tardigrade’s effect on the qubit follows the laws of electromagnetism and that “putting a speck of dust next to the qubit would have a similar effect”, since adding any mass to the system would have altered its frequency [7]. Additionally, the research has not been peer-reviewed or formally published, strengthening the idea that the research may not present any ground-breaking findings. Until further research is done by other teams of scientists, the claim that tardigrades were quantum entangled shouldn’t be seen as a fact.
Whilst there is a chance that the tardigrade has been successfully entangled and the research onto other similar creatures can follow, until it is peer-reviewed and published, this research remains a theory, just as quantum entanglement itself once was.
References
[1] Caltech Faculty, “What Is Entanglement and Why Is It Important?,” Caltech. [Online]. Available: https://scienceexchange.caltech.edu/topics/quantum-science-explained/entanglement. [Accessed 13 March 2022].
[2] L. Fuge, “Did Scientists really quantum entangle tardigrades?,” Cosmos, January 5, 2022. [Online]. Available: https://cosmosmagazine.com/science/physics/did-scientists-really-quantum-entangle-tardigrades/. [Accessed 13 March 2022].
[3] K. Arakawa, “Examples of Extreme Survival: Tardigrade Genomics and Molecular Anhydrobiology,” Annual Review of Animal Biosciences, vol. 10, no. 1, pp. 17-37, 2022. Available: https://doi.org/10.1146/annurev-animal-021419-083711.
[4] J. H. Crowe, F. A. Hoekstra, L. M. Crowe, “Anhydrobiosis,” Annual Review of Physiology, vol. 54, no. 1, pp. 579-599, 1992. Available: https://doi.org/10.1146/annurev.ph.54.030192.003051.
[5] K. S. Lee et al., “Entanglement in a qubit-qubit-tardigrade system,” New Journal of Physics, vol. 24, 2022. Available: https://doi.org/10.1088/1367-2630/aca81f.
[6] D. Natelson, “No, a tardigrade was not meaningfully entangled with a qubit,” Blogger, December 18, 2021. [Online]. Available: https://nanoscale.blogspot.com/search?q=quantum+entangled+tardigrade. [Accessed 13 March 2022].
[7] B. Brubaker, “Frequency Shifts Do Not Imply Quantum Entanglement,” Ben Brubaker, January 3, 2022. [Online]. Available: https://benbrubaker.com/frequency-shifts-do-not-imply-quantum-entanglement/. [Accessed 13 March 2022].
