Our purpose with **atom*innen**, is first to inform. In this section, you will find definitions that will help you better understand quantum physics if you are not (yet) a quantum scientist.

### Acoustics

Quantum acoustics refers to the study of the interaction between quantum mechanical systems and sound waves. It explores phenomena where quantum effects play a significant role in the behavior of acoustic waves or vice versa. This field sits at the intersection of quantum mechanics and acoustics, investigating how principles such as superposition, entanglement, and coherence manifest in acoustic systems, and how acoustic phenomena can be harnessed for quantum information processing, sensing, or metrology. Quantum acoustics encompasses various topics such as quantum-limited measurements of sound, acoustic analogs of quantum systems, quantum transducers for converting between acoustic and other forms of quantum information, and exploring quantum effects in macroscopic acoustic systems.

### Bose-Einstein condensation

### Electromagnetism

### Experimental physics

Quantum experimental physics is a branch of physics that focuses on the experimental investigation and verification of phenomena predicted by quantum mechanics, which is the fundamental theory governing the behavior of particles at the microscopic scale. This field involves designing and conducting experiments to test the principles and predictions of quantum mechanics, such as wave-particle duality, superposition, entanglement, and uncertainty principle. Quantum experimental physicists work with sophisticated equipment and techniques, such as particle accelerators, quantum computers, and quantum optics setups, to observe and manipulate quantum systems, often pushing the boundaries of our understanding of the quantum world. The goal is to gain insights into the fundamental nature of matter and energy at the quantum level and to develop practical applications based on quantum phenomena.

### Heisenberg Uncertainty Principle

### Optics

Quantum optics is a branch of quantum physics that deals with the study of the interaction between light (photons) and matter at the quantum level. It investigates phenomena such as the emission, absorption, transmission, reflection, and scattering of light, all of which occur in discrete, quantized units known as photons. Quantum optics explores how light behaves when it interacts with atoms, molecules, and other quantum systems. This field is crucial for understanding various phenomena such as** quantum entanglement, quantum interference, quantum coherence** and **quantum cryptography**. Overall, quantum optics plays a fundamental role in both fundamental research and practical applications, ranging from **quantum information** science to **precision metrology** and **quantum communication**.

### Quantum communication

Quantum communication is a field within quantum physics that deals with the transmission of information encoded in quantum states of particles. Unlike classical communication, which relies on classical bits (either 0 or 1), quantum communication employs qubits, which can exist in multiple states simultaneously due to the principles of superposition and entanglement.Quantum communication offers several advantages over classical communication, primarily in terms of security. One of its most prominent applications is quantum key distribution (QKD), which enables the creation of secure cryptographic keys that are theoretically immune to eavesdropping attempts. This is achieved through protocols such as BB84 or E91, which exploit the properties of quantum mechanics to detect any attempt at interception or measurement of the transmitted quantum states. Additionally, quantum communication holds potential for achieving communication protocols that are fundamentally secure and may enable tasks such as teleportation of quantum states and long-distance quantum entanglement for distributed quantum computing. However, current implementations are still largely experimental and face significant technological challenges in achieving practical scalability and reliability.

### Quantum computer

Device that exploits the new possibilities offered by quantum mechanics to tackle tasks hard or impossible to solve with our current classical (i.e. non quantum) computers.

### Quantum entanglement

Correlations between parts of a quantum system (a system obeying quantum physics) that cannot be present in classical systems (where classical physics works) that are an important resource in quantum computation.

### Quantum bit

Analogous to classical bits (0s and 1s) but with states that can be (a) in a coherent superposition, and (b) entangled.

### Quantum matter

Quantum matter refers to any material or substance whose behavior and properties are primarily governed by the principles of quantum mechanics. In classical physics, matter is typically described in terms of macroscopic properties like mass, volume, and density. However, at the quantum level, matter exhibits behaviors that are fundamentally different from classical physics. Key characteristics of quantum matter include **wave-particle duality**,**quantization, superposition, entanglement and tunneling.**

### Quantum mecanics

Quantum mechanics is the branch of physics that deals with the mathematical description of the motion and interaction of subatomic particles, such as electrons and photons. It provides a framework for understanding phenomena such as wave-particle duality, quantization of energy levels, superposition, and entanglement. In quantum mechanics, physical quantities are often represented by operators acting on wave functions, which are mathematical functions that describe the probability amplitude of finding a particle in a particular state. The theory is probabilistic in nature, meaning that it describes the behavior of particles in terms of probabilities rather than definite outcomes. Quantum mechanics has profound implications for our understanding of the nature of reality and has led to the development of numerous technologies, including quantum computers, quantum cryptography, and quantum sensors.

### Quantum sensing and metrology

Quantum sensing and metrology deal with the precise measurement and detection of physical quantities.

Quantum sensing involves using quantum systems, such as atoms, ions, or photons, to measure physical quantities with extremely high precision. These physical quantities could include magnetic fields, electric fields, gravitational fields, or even time itself. Quantum sensing takes advantage of the fundamental principles of quantum mechanics, such as superposition and entanglement, to achieve measurements that surpass the limitations of classical sensing methods. Examples of quantum sensing technologies include atomic clocks, magnetometers, and gravitational wave detectors.

Quantum metrology is the science and practice of making highly accurate measurements based on quantum principles. It focuses on developing techniques and technologies to achieve measurements with unprecedented precision and accuracy. Quantum metrology often involves manipulating and exploiting the quantum properties of particles and systems to enhance the sensitivity of measurement devices. This can include techniques such as entanglement-enhanced measurement, quantum interferometry, and squeezing. Quantum metrology has applications across various fields, including navigation, timekeeping, communication, and fundamental research.

### Quantum simulation

Quantum simulation is a technique used in quantum physics to simulate the behavior of quantum systems using another controllable quantum system. It involves replicating the dynamics of a complex quantum system that is difficult to study directly, such as a large molecule or a condensed matter system, using a simpler, more controllable quantum system that can be manipulated in a laboratory setting. The idea behind quantum simulation is to use a controllable quantum system, such as trapped ions, superconducting qubits, or ultracold atoms, to mimic the behavior of another quantum system of interest. By engineering the interactions between the simulated system and the controllable quantum system, researchers can study the properties and behavior of the simulated system under various conditions. Quantum simulation has the potential to provide insights into fundamental questions in physics, chemistry, and materials science, such as the behavior of strongly correlated electron systems, the dynamics of chemical reactions, and the properties of exotic materials like high-temperature superconductors. It also plays a crucial role in the development of quantum technologies, such as quantum computers and quantum simulators, by providing a platform for testing and validating quantum algorithms and protocols.

### Schrödinger's cat

### Theoritical physics

Theoretical physics encompasses the study of physical phenomena using mathematical models and theoretical frameworks.

### Thermodynamics

Quantum thermodynamics is a branch of physics that deals with the study of thermodynamic processes at the microscopic level, where the principles of quantum mechanics become significant. It merges the principles of quantum mechanics, which describe the behavior of particles at the smallest scales, with thermodynamics, which governs the macroscopic properties of systems with a large number of particles. In classical thermodynamics, systems are described by macroscopic variables such as temperature, pressure, and energy. However, at the quantum level, particles exhibit wave-particle duality, uncertainty, and other quantum phenomena, which can significantly affect the behavior of thermodynamic systems. Quantum thermodynamics seeks to understand and describe the thermodynamic properties of such systems, taking into account the quantum nature of particles and their interactions. It addresses questions such as the limits of efficiency for quantum engines, the role of quantum coherence in thermodynamic processes, and the behavior of quantum systems far from equilibrium. Overall, quantum thermodynamics provides a framework for understanding how quantum mechanics influences the thermodynamic behavior of systems at the microscopic level, leading to new insights into energy conversion processes, information processing, and the fundamental limits of thermodynamic efficiency.

### Wave-particle duality

Both light (electromagnetic 'waves', photons) and matter (electrons, atoms, ....) exhibit wavelike (interference, diffraction, ...) and particlelike behaviour in different situations (see examples such as double-slit experiments for both light and electrons, photoelectric effect).