Quantum computation, non-demolition measurements, and reflective control in living systems

V. P. Belavkin

Kae Nemoto, William J. Munro

Matthew Witten

Abir U. Igamberdiev

The smallest details of living systems are molecular devices that operate between the classical and quantum levels, i.e. between the potential dimension (microscale) and the actual three-dimensional space (macroscale). They realize non-demolition quantum measurements in which time appears as a mesoscale dimension separating contradictory statements in the course of actualization. These smaller devices form larger devices (macromolecular complexes), up to living body. The quantum device possesses its own potential internal quantum state (IQS), which is maintained for prolonged time via error-correction being a reflection over this state. Decoherence-free IQS can exhibit itself by a creative generation of iteration limits in the real world. To avoid a collapse of the quantum information in the process of correcting errors, it is possible to make a partial measurement that extracts only the error-information and leaves the encoded state untouched. In natural quantum computers, which are living systems, the error-correction is internal. It is a result of reflection, given as a sort of a subjective process allotting optimal limits of iteration. The IQS resembles the properties of a quasi-particle, which interacts with the surround, applying decoherence commands to it. In this framework, enzymes are molecular automata of the extremal quantum computer, the set of which maintains stable highly ordered coherent state, and genome represents a concatenation of error-correcting codes into a single reflective set. Biological systems, being autopoietic in physical space, control quantum measurements in the physical universe. The biological evolution is really a functional evolution of measurement constraints in which limits of iteration are established possessing criteria of perfection and having selective values.

Dario Melegari, Rabia Abdul Razaq, G. Minuto +1 more

Abstract We present a comparative study of two implementations of a variational quantum algorithm aimed at minimizing the energy of a complex quantum system. In one implementation, we extract the information of the energy gradient by projective measurements. In the second implementation, called the non-demolition approach, the gradient information is stored in a quantum detector, which is eventually measured. As prototypical examples, we study the energy minimization of the lithium-based molecules and then extend the analysis systems with increased complexity. We find that while both approaches are able to identify the energy minimum, the non-demolition approach has a clear advantage in terms of the overall computational resources needed. This advantage increases linearly with the complexity of the quantum system, making the non-demolition approach the ideal candidate to implement such variational quantum algorithms. Graphical abstract Schematic representation of the energy minimization process for the H2 and LiH molecules using direct measurement (DM) and quantum non-demolition measurement (QNDM) approaches. Both methods converge to the minimum energy with similar accuracy, but the QNDM approach requires significantly fewer quantum resources (up to 79% reduction in gate count for LiH), highlighting its efficiency for variational quantum algorithms

John Edward Gough, V. P. Belavkin