Articles & Reviews

Authored by RSF Research Staff

Quantum Zeno dynamics in a superconducting qubit

By: William Brown

The Greek philosopher Zeno of Elea posed several philosophical arguments that have become collectively known as Zeno’s paradoxes. One such argument is known as Zeno’s arrow paradox; the simplistic explanation of which is that in order for motion to occur an object must change its location, like an arrow flying to its target, yet at any instantaneous moment the arrow is motionless, and since, as Zeno posed, time is composed of a sequence of many such duration-less instants, then motion of the arrow is impossible. This paradox is actually highly salient to an understanding of the fundamental nature of motion and time, and hence the fundamentals of physics.

Zeno’s paradox has found its way into the lexicon of quantum mechanics in a class of phenomena known as quantum Zeno dynamics. As the name would indicate, quantum Zeno effects have to do with time evolution of a system, often with effects that are paradoxically counter to what is normally observed in quantum experimentation. For instance, frequent measurements of a quantum system can in fact arrest its evolution, delaying its decay -- even going so far as to decouple a system from its decohering environment. This is the opposite of what “measurements”, or interactions with the environment are normally thought to do in quantum mechanics theory.

Quantum Zeno Dynamics

In quantum Zeno dynamics, the decoherence rate of a quantum state can be either increased or decreased by how the system is coupled to the environment. When the time evolution or decay of a quantum state is frozen, it is referred to as the Zeno effect. An increased decay rate is known as the anti-Zeno effect, because instead of “freezing” the state of the quantum system in time, it accelerates its time evolution. Frequent measurements will alter how a quantum state, such as a qubit, will interact with the environment, essentially allowing control of quantum evolution with tunable environmental interactions.

Certain schemes of coupling a quantum system with the environment are referred to as “quasi-measurements”, as the interaction with the environment does not necessarily transmit information about the state of the quantum system – highlighting that the effect is not necessarily antithetical to the normal description of environmental decoherence in quantum theory.

in the June 14, 2017, issue of Physical Review Letters physicists describe the observation of quasi-measurements producing quantum Zeno effects. Their protocol used a qubit uniquely coupled to a thermal bath to produce both enhanced and diminished decay times. Researchers were able to show that by changing the frequency and type of interaction of the qubit with a noise-source they could arrest the evolution of the system, such that the qubit did not decohere or decay, or they could accelerate the decay.

The latest experiment was a first because “while Zeno effects, and more broadly Zeno dynamics, have been studied with superconducting qubits, the anti-Zeno effect has not yet been studied at the level of a single quantum system.”

Does the Zeno effect have relevance beyond quantum computing?

In addition to potential implications and applications in quantum computing, Resonance Science Foundation researchers are taking notice in the results because of potential implications in understanding the finely ordered and coherent state of the biological system. Just as quantum measurements are being utilized to stabilize the fragile state of the artificial qubit, similar mechanisms may be involved in stabilizing quantum states, natural qubits, in the biological system.

For instance, the quantum Zeno effect can be considered in evaluating how theories involving non-classical information processing dynamics in a strongly interacting environment like the cell may in fact be occurring. Information processing that may involve quantum correlation (entanglement) or nonlocal interaction have largely been summarily dismissed because of the presumed high amount of noise of the biological system.

Such a presumption, however, may be problematic or largely erroneous because the molecular structures of the biological system are in a highly ordered arrangement and are comprised of novel forms of matter that have been exquisitely fine-tuned by natural selection over billions of years. It is no stretch of the imagination that novel molecular forms that optimally capitalize on nature’s intrinsic properties, such as quantum informational dynamics, will have an immediate selective advantage – highly improved efficiency of photosynthesis and metabolism, greater environmental sensitivity, memory, responsiveness, and perhaps greater cognitive capabilities.

As such, biomolecules may not be comparable to the “simple matter” -- often times individual quanta like free photons and electrons -- used in experimentation where non-classical quantum phenomena are observed. The biological supramolecular assemblies of the cell are a special state of matter. And the large numbers of interacting units and their frequent interaction may in fact enable a certain degree of increased “quantumness” instead of being the primary source of decoherence as is naively assumed.

For instance, there are relatively new developments in quantum mechanics such as quantum discord, where the “quantumness” of correlations can be variable and present in certain mixed separable states – that is to say, quantum correlations that exist but that are not necessarily entanglement. In terms of the relatively high temperature of the biological system, a condition that is supposed to inhibit strong coherence, it has been shown that for a qubit pair in contact with a normally decohering environment, like a heat bath, the strength of correlations can actually increase with increasing temperature.

This brings us to the quantum Zeno effect, where measurements made in rapid succession can actually prolong the quantum coherency of a state. This is quite the paradoxical situation, because measurements are supposed to be the agents of decoherence and decay of quantum states, yet here increased interaction can do the opposite. Leading to the question of whether the frequent interactivity / communication of components of the supramolecular assemblies of the biological system may work to prolong and enhance the lifetime of strongly coupled and coherent states.

Relevant supramolecular assemblies include the plasma membrane, mitochondria, DNA, and microtubules. Mitochondria and microtubules are significant in that they can theoretically function as quantum electrodynamic cavities, where interactions between light, atomically ordered water, and electron dipole moments can form quantum coherent states for intra- and inter-cellular dissipation-less solitonic energy transfer and quantum teleportation.

Mitochondria and microtubules, in close association, form dendritic networks in which coherent photon emission can be channeled through the cell. Coherent photons modulate the electronic properties of biomolecules, a QED-like mechanism that can be used to holographically store information as well as initiate physicochemical responses in the cellular system. This system is referred to as the holographic information network of the mitochondrial reticular matrix.

Intercellular networks are formed by gap junctions and tunneling nanotubes, the latter of which contain filamentous mitochondria and microtubules that can connect multiple cells, enabling gestalt information transmission and processing. Quantum coherence and nonlocal phenomena can enable the cellular information system to perform massively parallel processing, enabling remarkable organizational synergy and unified orchestration of function.

Zeno effect, quantum biology, and spacetime geometry – a unified picture

As explained in the manuscript the Unified Spacememory Network by Haramein et alia, nonlocality is a result of spacetime geometry, such that entanglement is the manifestation of multiply-connected spacetime architecture, i.e. a Planckian micro-wromhole network, or quantum spacetime foam. This multiply-connected geometry represents a kind of hyperspace, comprised of information resulting from the quasi-instantaneous communicativity of all spacetime frames across spatial and temporal domains. The interaction across this transtemporal, nonlocal connectivity network is one way in which memory, recorded in the entanglement connectivity patterns, is produced. Hence the moniker, spacememory network.

This has important implications for considerations of entanglement and other quantum processes of nonlocality in the biological system. Specifically, entanglement necessarily results from the underlying spacetime geometry – therefore any such process interlaces functions of the biological system with the informational manifold of the spacememory network. A possibly important dynamic that, theoretically, would be intricately and inextricably involved in processes of evolution, development, sentience and memory of the living system.

Experiments that advance our understanding of quantum entanglement and other phenomena involving nonlocality, like the testing of quantum Zeno dynamics with qubit stability, are important for developing a deeper understanding of how nature may be utilizing quantum dynamics, particularly in the biological system. While theoretical considerations of quantum coherence, entanglement, and other nonlocal phenomena in the living organism remain relatively controversial, the true test of these ideas will be to conduct experiments aimed at observing just such phenomena. Resonance Science Foundation researchers are designing experimental protocols to do exactly that, so that soon they will be able to experimentally test whether or not the entanglement and information exchange with the nonlocal spacememory network is in fact supported observationally and empirically.


More to Explore:

Quantum Zeno effects from measurement controlled qubit—bath interactions

Experimental realization of quantum zeno dynamics

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