Elementary Cycles Theory is a self-consistent, unified formulation of quantum and relativistic physics. Here we introduce its basic quantum aspects. On one hand, Newton's law of inertia states that every isolated particle has persistent motion, i.e. constant energy and momentum. On the other hand, the wave-particle duality associates a space-time recurrence to the elementary particle energy-momentum.Paraphrasing these two fundamental principles, Elementary Cycles Theory postulates that every isolated elementary constituent of nature (every elementary particle) must be characterized by persistent intrinsic space-time periodicity. Elementary particles are the elementary reference clocks of Nature. The space-time periodicity is determined by the kinematical state (energy and momentum), so that interactions imply modulations, and every system is decomposable in terms of modulated elementary cycles. Undulatory mechanics is imposed as constraint "overdetermining" relativistic mechanics, similarly to Einstein's proposal of unification. Surprisingly this mathematically proves that the unification of quantum and relativistic physics is fully achieved by imposing an intrinsically cyclic (or compact) nature for relativistic space-time coordinates. In particular the Minkowskian time must be cyclic. The resulting classical mechanics are in fact fully consistent with relativity and reproduces all the fundamental aspects of quantum-relativistic mechanics without explicit quantization. This "overdetermination" just enforces both the local nature of relativistic space-time and the wave-particle duality. Besides the unified description of relativistic and quantum dynamics, Elementary Cycles Theory implies a fully geometrodynamical formulation of gauge interactions which, similarly to gravity and general relativity, is inferred as modulations of the elementary space-time clocks. This brings novel elements to address most of the fundamental open problems of modern physics.arXiv:1707.00677v1 [physics.gen-ph] 3 Jul 2017 E. Three dimensional Schrödinger problems, Coulomb potential, quantum numbers and Fock space 49 F. Condensed matter and the role of the temperature 51 1. Matsubara theory 52 2. Dirac quantization for magnetic monopoles 53 3. Superconductivity and graphene physics 53 V. Implications in modern physics 54 A. Gauge interactions from space-time geometrodynamics 54 B. Correspondence with extra-dimensional theories and string theory 56 C. Time cycles and the interpretation of time flow 57 VI. Conclusions 58 References 59 To the memory of my father and my brother. I. INTRODUCTION Elementary Cycles Theory (ECT) is a fully consistent formulation of Quantum Mechanics (QM), relativistic physics, Gauge interactions and other aspects of modern physics, obtained by postulating an intrinsically cyclic nature for Minkowskian space-time. As proven in many previous peer-reviewed papers, e.g. [1-14, 27-29], it provides an unprecedented, complete, exact, unified description of quantum and relativistic physics. The idea is based on the empi...