The transport properties of condensed matter are traditionally described in terms of charge currents, spin currents, and heat currents, each associated with a distinct flux of physical quantities. In this work we introduce a new concept, the internal information flow, denoted by J_I, which quantifies the rate of change of quantum information residing within a material system. Unlike conventional currents, J_I is not directly associated with a conserved charge or energy but rather with the redistribution of correlations and entanglement among the degrees of freedom. We formulate J_I in a rigorous operator framework, show that it obeys continuity-like equations, and illustrate its distinct physical consequences through several model systems. We further discuss possible measurement schemes based on quantum tomography and weak measurement techniques, and highlight the potential of internal information flow to bridge quantum information science and materials physics. The theoretical framework presented here opens a new avenue for exploring quantum thermodynamics, quantum phase transitions, and ultimately paves the way for a deeper understanding of the interplay between information and matter.
The transport properties of condensed matter are traditionally described in terms of charge currents, spin currents, and heat currents, each associated with a distinct flux of physical quantities. In this work we introduce a new concept, the internal information flow, denoted by J_I, which quantifies the rate of change of quantum information residing within a material system. Unlike conventional currents, J_I is not directly associated with a conserved charge or energy but rather with the redistribution of correlations and entanglement among the degrees of freedom. We formulate J_I in a rigorous operator framework, show that it obeys continuity-like equations, and illustrate its distinct physical consequences through several model systems. We further discuss possible measurement schemes based on quantum tomography and weak measurement techniques, and highlight the potential of internal information flow to bridge quantum information science and materials physics. The theoretical framework presented here opens a new avenue for exploring quantum thermodynamics, quantum phase transitions, and ultimately paves the way for a deeper understanding of the interplay between information and matter.
In conventional condensed‑matter physics, transport phenomena are usually described by electric current J_E and heat current J_Q, each associated with the flow of charge or energy. In this work we introduce a fundamentally distinct quantity, the internal information current J_I, which characterises the spatial transport of quantum information within a material. By deriving a continuity equation for the local von Neumann entropy density ρ_I and identifying the corresponding flux J_I, we establish a unified framework that connects quantum information theory with transport theory. The formalism naturally incorporates coherence and entanglement as intrinsic sources of information flow, thereby revealing new mechanisms for energy conversion, quantum state control, and material functionality. We discuss potential experimental signatures in ultracold atomic lattices, solid‑state qubits, and topological insulators, and outline the implications for quantum thermodynamics, quantum sensing, and the design of next‑generation quantum devices. This novel perspective offers a pathway toward harnessing information as a physical resource in quantum matter, with prospective relevance to the Nobel‑level discovery of quantum materials that bridge information and matter.
The motion of electrons in a quantum system is traditionally described in terms of charge transport, yielding an electric current density J_e. In this work we propose that the same quantum mechanical motion also carries an intrinsic information flow, denoted J_I, which quantifies the propagation of the quantum state's informational content through space and time. We develop a formalism in which the orbital probability density ρ(r, t) and its associated phase θ(r, t) give rise to two coupled continuity equations: one for charge and one for information. The information current is expressed in terms of gradients of the phase and the logarithm of the amplitude of the wavefunction, thereby revealing a direct link between the spatial structure of the orbital and the distribution of quantum information. The framework is applied to two-dimensional quantum materials, where the interplay between electronic band topology and information flow opens avenues for designing devices that manipulate information without dissipative charge transport. The concept of orbital information current lays the foundation for an emerging discipline, "information physics," which seeks to harness quantum informational degrees of freedom for practical applications.
The concept of entropy is central to both classical thermodynamics and quantum information science. In conventional treatments, entropy is a scalar quantity associated with a statistical ensemble or a quantum state. This paper introduces a novel perspective in which quantum systems support an entropy flow field, denoted J_S(x,t), analogous to the heat current in classical thermodynamics. We develop a rigorous theoretical framework for defining and calculating entropy flow in closed and open quantum systems, and we propose a method for imaging this flow by mapping local entropy production rates onto spatial coordinates. The resulting Quantum Entropy Flow Imaging (QEFI) technique offers a powerful diagnostic tool for probing nonequilibrium quantum dynamics, revealing hidden structure in entanglement propagation, and bridging the gap between quantum information and thermodynamic concepts. While the experimental implementation of QEFI is left for future work, we outline how quantum simulators and ultracold atomic gases can be employed to test the predictions. The potential to observe entropy currents in quantum devices opens new avenues for exploring fundamental questions about the nature of entropy, information flow, and their role in quantum technologies.
Electronic structure in solids is traditionally described by the distribution of electron energies and the occupation of momentum states. In many-body systems, however, the reorganization of electrons among atomic orbitals can occur without a corresponding change in total electronic energy, yet it may entail a profound rearrangement of quantum correlations and information content. This paper introduces the concept of orbital entropy, a measure of the quantum informational disorder associated with the occupation of local orbital degrees of freedom, and defines its dynamical counterpart, the orbital entropy flow J_S^{orb}. We formulate a continuity equation that couples J_S^{orb} to the orbital current operator, and demonstrate that this flow is distinct from conventional energy and charge currents. The formalism is applied to model Hamiltonians relevant to Mott insulators and Hund's metals, revealing that orbital entropy can be selectively pumped by external fields and that its redistribution governs the temperature dependence of transport coefficients. The existence of a conserved orbital entropy current suggests the possibility of an orbital thermodynamics framework, analogous to conventional thermodynamics but grounded in quantum many-body theory. Potential experimental probes, including ultrafast pump–probe spectroscopy and resonant inelastic X-ray scattering, are discussed as routes to detect J_S^{orb} and to map its spatial variation in correlated crystals. This work opens a new avenue for understanding entropy management in quantum materials and for engineering devices that exploit orbital degrees of freedom for energy conversion and information processing.
In the realm of condensed matter physics, the interplay between quantum information and material properties has emerged as a fertile area of inquiry. Here we propose a novel conceptual framework, termed Information Pressure in Quantum Matter (IPQM), in which changes in the informational state of a quantum system generate an effective mechanical pressure, P_I, that influences the energetic landscape and phase stability of the material. We formulate a quantitative description of P_I based on the von Neumann entropy, S = -Tr(ρ ln ρ), of the reduced density matrix ρ associated with a subsystem. The effective pressure is defined as P_I = -k_B T (∂S/∂V)_T, where V is the volume of the subsystem and T is the temperature. By coupling P_I to the conventional Gibbs free energy, G = U - TS + PV, we derive modified equations of state that predict shifts in critical points and the emergence of new phases when the system undergoes controlled information manipulation. We illustrate the utility of IPQM with several theoretical examples, including spin chains, topological insulators, and superconducting lattices, where information-driven perturbations can tune magnetic ordering, band topology, and pairing symmetry. The IPQM framework provides a unified language for describing how information processing operations, such as unitary gates, measurements, and error correction, can be leveraged to engineer quantum matter with desired properties. This perspective opens pathways toward the design of pressure-free, information-controlled quantum devices and suggests a new class of quantum thermodynamic cycles that exploit information flow as a resource.
Entropy is a fundamental quantity in both classical and quantum physics, usually regarded as a scalar measure of disorder or uncertainty. In this work we propose a novel viewpoint: the existence of an entropy flow field in quantum systems, denoted by J_S(x,t). This field, analogous to the conventional heat current, encapsulates the spatiotemporal transport of informational entropy within a many‑body wavefunction or density matrix. We develop a rigorous mathematical framework for J_S(x,t), derive its properties from the Lindblad master equation, and discuss how it unifies concepts from quantum thermodynamics and quantum information theory. The core contribution is a practical imaging protocol—Quantum Entropy Flow Imaging (QEFI)—that reconstructs the spatial distribution of J_S(x,t) from measurable observables in quantum simulators or engineered quantum devices. The method offers a new diagnostic tool for exploring nonequilibrium dynamics, entanglement propagation, and thermalization pathways. Potential applications range from characterizing heat transport in ultracold gases to optimizing quantum control protocols in noisy intermediate‑scale quantum processors.