Computer scientists have long known that evolution is an algorithmic process that has little to do with the nature of the beasts it creates. Instead, evolution is set of simple steps that, when repeated many times, can solve problems of immense complexity; the problem of creating the human brain, for example, or of building an eye.
And, of course, the problem of creating life. Put an evolutionary algorithm to work in a virtual environment and it doesn’t take long to create life-like organisms in silico that live and reproduce entirely within a virtual computer-based environment.
This kind of life is not carbon-based or even silicon-based. It is a phenomenon of pure information. But if the nature of information allows the process of evolution to be simulated on an ordinary computer, then why not also on a quantum computer? The resulting life would exist in virtual quantum environment governed by the bizarre laws of quantum mechanics. As such, it would be utterly unlike anything that biologists have ever encountered or imagined.
But what form might quantum life take? Today we get an insight into this question thanks to the work of Unai Alvarez-Rodriguez and a few pals at the University of the Basque Country in Spain. They have simulated the way life evolves in a quantum environment and use this to propose how it could be done in a real quantum environment for the first time. “We have developed a quantum information model for mimicking the behavior of biological systems inspired by the laws of natural selection,” they say.
The steps involved in evolution are well known. It begins with a population of individuals capable of reproducing. Next, there must be a process of selection that allows better adapted individuals to produce more offspring than less well-adapted ones. And there must also be a way of introducing change between one generation and the next through random mutation or by sexual recombination.
The final ingredient is iteration. When these steps are repeated over many countless generations, the individuals that emerge are those that have evolved to survive best in the given environment.
At least, that’s how it works in the classical world both in real environments and in virtual ones. But the quantum world is different. At first glance, it’s not entirely clear how something similar could occur in a quantum environment.
But Alvarez-Rodriguez and co have developed a way to do it. They start by creating quantum individuals capable of reproducing in a quantum environment.
These creatures consist of two parts. The first plays the role of DNA; it is the information that is passed on from one generation to the next. The second plays the role of the creature’s body, it is the part that interacts with the environment, ages, and eventually dies. These parts act like a genotype and phenotype for the organism.
The creatures can reproduce in two ways. The first is asexual—the quantum DNA separates from its body and is then available to join with another quantum body to create a new individual. That creates an identical copy of the original but mutations can occur by means of physical processes that randomly change the body between lives.
The second way is sexual reproduction. When two creatures meet, they reproduce by exchanging quantum DNA to produce a new genome that has elements of both. This is then available to join with a body to create an organism with an entirely new genotype.
Of course, the mechanics that govern all this is entirely quantum in nature. The operation that passes information from one generation to the next is a form of quantum cloning that transfers the information from one particle to another. Mutation is a kind of logic operation, like a rotation, that changes the quantum information a particle carries.
This kind of life would have some unique properties. “The entanglement among different individuals allows us to clone the classical information and propagate the quantum coherences of the initial quantum living units to the successive generations,” says Alvarez-Rodriguez and co.
In other words, the “quantumness” passes from one generation to the next via quantum entanglement. So each individual and its descendants share a powerful bond since entangled particles effectively share the same existence.
But this has important computational consequences. The resulting simulation is so complex that it can be done on a classical computer only for a small number of generations and this severely limits what can be learned about the nature of quantum life.
What’s needed, of course, is a purely quantum model. And here Alvarez-Rodriguez and co say this ought to be possible with technologies that are available now.
They point out that the simplest kinds of quantum life need only consist of two qubits—one representing the genotype and the other representing the phenotype. These qubits merely need to be joined together.
This ought to be relatively straightforward with trapped ions, for example, that physicists have considerable experience dealing with. In this case, the quantum information can be stored in the various energy levels of an ion. The interactions between ions and the qubits they contain can then be mediated via logic operations that combine these states, rotate them, and so on. Similar operations are also possible with photons and superconducting qubits.
That’s interesting work with exciting potential. What is needed now is somebody with a trapped ion facility or a quantum optics bench and a few spare hours to play around with this kind of model. Such a model could explore how quantum individuals evolve in specific environments.
Such an experiment has the potential to change the way researchers think about life and, indeed, quantumness. Whenever the idea of quantum life comes up, a simple question soon arises. That is how quantum life experiments can throw light on the origin of life itself.
The thinking on this topic is changing rapidly. It wasn’t so long ago that biologists swore blind that quantum processes could never play a role in the mechanisms of life or in its origin.
Today, they’re not so sure. Quantum processes seem to lie at the heart of all kinds of biological phenomenon such as photosynthesis, our sense of smell, and even bird navigation.
Only a brave researcher would argue that they could not have played a role in the origin of life. And it’s work like this that could help explore this important question in more detail than ever before.
Ref: arxiv.org/abs/1505.03775 : Artificial Life in Quantum Technologies