In strongly correlated quantum liquids, topological and local defects can give rise to emergent excitations that are neither conventional phonons nor magnons. We introduce the concept of Quantum Liquid Defect Quasiparticles (QLDQ), a class of collective modes generated by the interplay of quantum fluctuations and structural imperfections. These quasiparticles, denoted \(D_q\), possess dispersion relations that mirror those of phonons but arise from the defect core rather than lattice vibrations. Using a field‑theoretical approach, we derive the effective action for a defected quantum liquid, identify the spectrum of \(D_q\) modes, and analyze their statistical, topological, and thermodynamic signatures. We discuss how the presence of \(D_q\) modifies the low‑temperature behavior of superfluid systems and outline potential routes to detect them in ultracold atom experiments and low‑temperature condensed‑matter platforms. The discovery of QLDQ would open a new avenue for exploring elementary excitations in quantum fluids and may have implications for quantum technologies that exploit defect‑based coherence.
In strongly correlated quantum liquids, topological and local defects can give rise to emergent excitations that are neither conventional phonons nor magnons. We introduce the concept of Quantum Liquid Defect Quasiparticles (QLDQ), a class of collective modes generated by the interplay of quantum fluctuations and structural imperfections. These quasiparticles, denoted (D_q), possess dispersion relations that mirror those of phonons but arise from the defect core rather than lattice vibrations. Using a field‑theoretical approach, we derive the effective action for a defected quantum liquid, identify the spectrum of (D_q) modes, and analyze their statistical, topological, and thermodynamic signatures. We discuss how the presence of (D_q) modifies the low‑temperature behavior of superfluid systems and outline potential routes to detect them in ultracold atom experiments and low‑temperature condensed‑matter platforms. The discovery of QLDQ would open a new avenue for exploring elementary excitations in quantum fluids and may have implications for quantum technologies that exploit defect‑based coherence.
In many-body quantum systems, the elementary excitations that carry energy and momentum are usually understood as phonons, rotons, or other well‑studied quasi‑particles. In this work we propose a new class of collective excitations, termed information phonons, that exist in quantum liquids. Unlike conventional phonons, an information phonon is defined by a field operator φ_I that carries an additional degree of freedom encoding classical or quantum information. We construct a minimal model Hamiltonian that describes the coupling between the density fluctuations of the liquid and the information field, derive the dispersion relation for φ_I, and analyze its properties. Theoretical analysis shows that the information phonon can propagate with a velocity distinct from the sound velocity, possesses a non‑trivial topological structure, and can be manipulated by external fields. We discuss the implications of these excitations for quantum information processing, suggesting that IPQLs could provide a new platform for robust quantum memories and information transport in strongly correlated media. The discovery of such quasi‑particles opens a promising avenue toward realizing novel quantum technologies and deepening our understanding of emergent phenomena in quantum liquids.
In many-body quantum systems, the elementary excitations that carry energy and momentum are usually understood as phonons, rotons, or other well‑studied quasi‑particles. In this work we propose a new class of collective excitations, termed information phonons, that exist in quantum liquids. Unlike conventional phonons, an information phonon is defined by a field operator φ_I that carries an additional degree of freedom encoding classical or quantum information. We construct a minimal model Hamiltonian that describes the coupling between the density fluctuations of the liquid and the information field, derive the dispersion relation for φ_I, and analyze its properties. Theoretical analysis shows that the information phonon can propagate with a velocity distinct from the sound velocity, possesses a non‑trivial topological structure, and can be manipulated by external fields. We discuss the implications of these excitations for quantum information processing, suggesting that IPQLs could provide a new platform for robust quantum memories and information transport in strongly correlated media. The discovery of such quasi‑particles opens a promising avenue toward realizing novel quantum technologies and deepening our understanding of emergent phenomena in quantum liquids.
In many-body quantum systems at ultra‑low temperatures, the collective behavior of particles can give rise to exotic states of matter such as superfluids and quantum liquids. These states exhibit macroscopic quantum coherence and support topological excitations, yet their internal mechanical response has traditionally been described only by local thermodynamic variables such as pressure, density, and temperature. In this work we introduce the concept of a topological pressure field, denoted PT(x), which captures the influence of non‑trivial topological order on the local mechanical pressure within a quantum liquid. The proposed field is derived from a gauge‑invariant formulation of the quantum stress tensor that incorporates Berry curvature and Chern‑Simons terms. We show that PT(x) is non‑zero only in regions where the quantum state hosts topological defects such as quantized vortices or skyrmion‑like textures. Using a simplified model of a two‑dimensional superfluid film, we calculate the spatial profile of PT(x) around a vortex core and predict measurable deviations from the classical pressure distribution. The existence of PT(x) implies that quantum liquids possess an additional mechanical degree of freedom that is purely topological. This insight opens a pathway to experimentally detect topological pressure via precision pressure sensors in superfluid helium or cold‑atom Bose‑Einstein condensates, and suggests new avenues for engineering quantum fluid devices that exploit topological mechanics.
The paradigm of Landau Fermi liquid theory has successfully described the low-energy behavior of numerous metallic systems. However, a growing number of experimental observations in strongly correlated electron materials, such as high-temperature superconductors and heavy fermion compounds, defy this conventional description, exhibiting what is known as non-Fermi liquid (NFL) behavior. These exotic states lack well-defined quasiparticle excitations, displaying anomalous scaling laws and transport properties. Ultracold atomic gases have emerged as highly controllable quantum simulators for strongly correlated matter, offering unprecedented access to tunable interaction strengths, dimensionality, and lattice geometries. This paper explores the potential of ultracold fermionic gases to unveil and characterize NFL behavior. We review the theoretical underpinnings of Landau Fermi liquid theory and its breakdown, survey prominent theoretical models for NFL states, and highlight experimental techniques in ultracold atomic systems pertinent to their detection. Specific attention is given to phenomena such as the BCS-BEC crossover, quantum criticality, and pseudogap phases in ultracold fermions, where strong interactions are expected to lead to deviations from quasiparticle descriptions. We discuss experimental signatures like anomalous spectral functions, linear-in-temperature resistivity analogs, and deviations in thermodynamic properties, proposing how these could be observed and analyzed in current and future ultracold atom platforms. This research aims to leverage the purity and tunability of atomic gases to gain fundamental insights into the nature of NFL states, contributing to a broader understanding of quantum many-body physics beyond the conventional quasiparticle picture.
Quantum liquids, such as liquid helium and ultracold atomic gases, exhibit complex collective behaviors that traditional linear response theory fails to fully capture. In this work, we propose the theoretical framework of Hidden Sound Velocity in Quantum Liquids (HSVQL), hypothesizing the existence of multiple undiscovered collective velocities denoted as v_1, v_2, ..., v_n beyond standard propagation modes. By employing higher-order response theory, specifically analyzing the third-order susceptibility chi^(3) and nonlinear correlation functions, we demonstrate that nonlinear coupling channels reveal these hidden modes. We formulate a comprehensive hydrodynamic and microscopic theory to derive dispersion relations and quasiparticle characteristics, opening a new paradigm for uncovering novel excitations in strongly interacting many-body systems.
The study of strongly correlated quantum matter has revealed numerous exotic phases beyond the conventional Landau Fermi liquid paradigm. Non-Fermi liquid (NFL) behavior, characterized by the breakdown of the quasiparticle concept and anomalous scaling laws for thermodynamic and transport properties, is a central theme in this field. While extensively investigated near quantum critical points in condensed matter systems, the emergence of NFL states in non-equilibrium, driven quantum systems, particularly in synthetic quantum matter platforms such as ultracold atomic Bose-Fermi mixtures, remains a frontier of research. This paper explores the theoretical framework and potential mechanisms for the emergence of NFL behavior in Bose-Fermi mixtures subjected to periodic driving (Floquet engineering) or quantum quenches. We review the fundamental properties of Fermi liquids and NFLs, delve into the intricacies of Bose-Fermi mixtures and non-equilibrium dynamics, and propose a methodology for investigating such emergent phenomena. We discuss expected experimental signatures, including anomalous spectral functions, power-law resistivity, and altered entanglement properties, providing a comprehensive perspective on how driving can sculpt novel quantum phases. The findings suggest a rich interplay between bosonic and fermionic degrees of freedom under non-equilibrium conditions, potentially leading to new avenues for quantum control and the discovery of universal NFL physics.