With the advance of superconducting quantum computing and the attempts of extending its operating range to higher temperatures, a special attention is paid to nanostructured quantum circuits. In particular, quasi one-dimensional quantum wires with phase slip centers are argued to be promising structures for the next generation of quantum computers. In its turn, this stimulates revisiting the question about the possibility of quantum processing of information in quasi one-dimensional structures in the nervous system, specifically the brain, in living organisms, especially in the light of recent findings that suggest robust room-temperature superconductivity in these structures. The early theories of superconductivity were in favor of its quasi one-dimensional nature, and the recent findings suggest that reducing dimensions of a system could be a good approach for increasing the critical temperature of a material. Here, based on experimental data, it is argued that both room-temperature superconductivity and quantum processing of information are possible in the microtubules that are abundant in the nervous system and form the scaffolding of every cell in advanced living organisms. The origin of superconductivity in microtubules, and the way in which quantum processing of information may take place in them, are discussed. The role of Josephson oscillations in processing and exchange of information is emphasized.
With the advance of superconducting quantum computing and the attempts of extending its operating range to higher temperatures, a special attention is paid to nanostructured quantum circuits. In particular, quasi one-dimensional quantum wires with phase slip centers are argued to be promising structures for the next generation of quantum computers. In its turn, this stimulates revisiting the question about the possibility of quantum processing of information in quasi one-dimensional structures in the nervous system, specifically the brain, in living organisms, especially in the light of recent findings that suggest robust room-temperature superconductivity in these structures. The early theories of superconductivity were in favor of its quasi one-dimensional nature, and the recent findings suggest that reducing dimensions of a system could be a good approach for increasing the critical temperature of a material. Here, based on experimental data, it is argued that both room-temperature superconductivity and quantum processing of information are possible in the microtubules that are abundant in the nervous system and form the scaffolding of every cell in advanced living organisms. The origin of superconductivity in microtubules, and the way in which quantum processing of information may take place in them, are discussed. The role of Josephson oscillations in processing and exchange of information is emphasized.
Dynamical activities within living eukaryotic cells are organized by microtubules, main structural components of the cytoskeleton and cylindrical polymers of the protein tubulin. Evidence and theoretical models suggest that states of tubulin may play the role of “bits ” in classical microtubule computational automata. The advent of quantum information devices, key roles played by quantum processes in protein dynamics, and coherent ordering in the cell cytoplasm further suggest that microtubules may function as quantum computational devices, and that mesoscopic and macroscopic quantum states are characteristic of living systems. In this paper new results from molecular dynamics simulation based on recently obtained atomic structure of tubulin are presented which provide support for classical and quantum modes of microtubule information processing. 1. Introduction: Cytoplasm
Quantum computing holds the promise of a novel form of information processing in which data resides in quantum states. By exploiting superpositions and entanglement among these states, quantum logic operations are expected to far surpass conventional digital logic in certain classes of problems. To realize this prospect, we employ superconducting circuits at millikelvin temperatures. The nonlinearity of a Josephson tunnel junction enables a two-level quantum system, or qubit, with excitation energy in the microwave regime. Key recent advances in such devices are the demonstration of robust and simple multi-qubit gates, the integration of superconducting qubits into arrays of four or more, and gate fidelities reaching 99%. [1,2,3]
The work involves a study of physical phenomena that take place at very small length scales, below one micro-meter. At temperatures roughly below one degree Kelvin, quantum-mechanical effects may rule in electronic transport. Macroscopic quantum-coherent effects that occur in metallic superconducting microstructures, are particularly intriguing. Large-scale quantum information processing is widely believed to be attainable utilizing such physical systems. This work concentrates on answering the question of how the described quantum-mechanical systems may be used as sensitive measuring devices. Considerable attention is paid to energy-storing metallic microstructures whose electrical properties resemble those of the familiar inductor or capacitor. This research involves primarily experimental investigations conducted around temperatures of 0.1 Kelvin. Methods both at low and at radio frequencies have been used. The experimental findings have been modelled theoretically, and theoretical concepts for new physical phenomena have been introduced. An inductively measured radio-frequency Cooper-pair transistor, the L-SET, has been developed and experimentally verified in this work. Being highly sensitive, fast, and non-invasive, the L-SET appears to be the most promising method for measuring electric charge. Sensitivity in charge measurements of 20 millionths of the electron charge (micro-e) within one second, and an input bandwidth of 100 MHz, have been demonstrated. It has been shown theoretically that the ultimate measurement accuracy is about 0.1 micro-e within a second. A new phase detector based on the Cooper-pair transistor has been proposed. This system has also been shown to be potentially usable as a quantum bit. A new type of radio-frequency single-electron transistor built using a multi-walled carbon nanotube has been fabricated and operated. Technologies have been developed in order to make the physical nano- or microstructures. A method has been presented to fabricate non-superconducting tunnel junctions. Consequences of the inverse superconducting proximity effect on the studied superconducting structures were considered. Measurement procedures were investigated for a new low-noise nanoamplifier, the Bloch-oscillating transistor. Single superconducting tunnel junctions were tested as detectors of energy states of the environment, or of noise.
The existence of living organisms in the mesoscopic realm may be quite nontrivial and actuallymay emerge from the interplay between quantum mechanics and gravity. On one side, quantumbiology investigates how quantum mechanical phenomena, such as superposition, entanglement,and tunnelling, contribute to biological processes. These quantum effects, once thought to beirrelevant in the “warm, wet, and noisy” environment of living organisms due to decoherence, havebeen found to play significant roles in various biological systems, from photosynthesis to enzymecatalysis. On the other side, gravitational forces have been implicated in the organization ofmicrotubules, which are essential for maintaining cellular structure and function. Recent studieshave demonstrated that gravitational forces can induce three-dimensional chromosomal conformational changes, which are associated with rapid transcriptional responses in human T cells. Sometheories propose that gravity might play a role in decoherence, such as in the Penrose-Hameroffmodel, which proposes that quantum coherence in microtubules could be the basis for consciousawareness and quantum computing-like information processing, with gravity playing a role in thecollapse of the quantum wave function. The model predictions that microtubules can support longrange coherent phenomena have been confirmed by experimental observations of superradiancefrom mega-networks of tryptophan UV-excited transition dipoles, particularly in microtubulearchitectures. Another experimental research highlights that microtubule network exhibits ahierarchy of three-fold resonant frequency patterns across biological scales – from tubulin proteinsto microtubules and neurons. This suggests a quantum-to-classical transition governed by scalefree dynamics, potentially underlying information processing in the brain. A very intriguing fact isthat at the most fundamental level of the origin of life, the standard genetic code, we can observethe scale-free computing that arises from arithmetic regularities of the nucleon numbers related tothe code’s numerous symmetries. Given that some of these symmetries probably originate fromdifferent evolutionary epochs, such scale-free computing may be a latent background mechanismof the organization of the genetic code and therefore relevant to natural computing.
Quantum computing is a novel paradigm for information processing that promises computational speedup for certain computational tasks while not being driven by Moore's law. Superconducting circuits based on Josephson junctions are one of the leading approaches for implementing the quantum bits, or qubits, in a quantum processor. Most superconducting qubit architectures involve circuit quantum electrodynamics, where the qubits are analogous to artificial atoms that are coupled to superconducting linear resonant cavities. This scheme allows for the readout of individual qubits, the manipulation of single-qubit states, and the generation of entanglement between qubits. The performance of current state-of-the-art systems is limited by decoherence of the qubits and associated gate errors. Nonetheless, experiments have been performed that already demonstrate a significant computational speedup compared to classical processing. Future implementations of fault-tolerant quantum computers will require the development of quantum error correction. Initial tests of elements of error correction in superconducting qubit arrays are underway.
Superconducting circuits based on Josephson junctions can exhibit macroscopic quantum coherence.Quantum computation with superconducting circuits is one of the most important research directions in the field of quantum information.Moreover,the study of the physical properties of superconducting circuits is an interdisciplinary area of both condensed matter physics and quantum optics.A brief overview is presented of the main results and advancements achieved so far,as well as future prospects,in the area of superconducting quantum computation.