WE – Q

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Quality of life

Quality of life (QOL) is an overarching term for the quality of the various domains in life. It is a standard level that consists of the expectations of an individual or society for a good life. These expectations are guided by the values, goals and socio-cultural context in which an individual lives. It is a subjective, multidimensional concept that defines a standard level for emotional, physical, material and social well-being. It serves as a reference against which an individual or society can measure the different domains of one’s own life. The extent to which one’s own life coincides with this desired standard level, put differently, the degree to which these domains give satisfaction and as such contribute to one’s subjective well-being, is called life satisfaction.


Quantum chemistry

Quantum chemistry, also called molecular quantum mechanics, is a branch of chemistry focused on the application of quantum mechanics to chemical systems. Understanding electronic structure and molecular dynamics using the Schrödinger equations are central topics in quantum chemistry.

Chemists rely heavily on spectroscopy through which information regarding the quantization of energy on a molecular scale can be obtained. Common methods are infra-red (IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and scanning probe microscopy. Quantum chemistry studies the ground state of individual atoms and molecules, and the excited states, and transition states that occur during chemical reactions.


Quantum computing

Quantum computing is the exploitation of collective properties of quantum states, such as superposition and entanglement, to perform computation. The devices that perform quantum computations are known as quantum computers. They are believed to be able to solve certain computational problems, such as integer factorization (which underlies RSA encryption), substantially faster than classical computers. The study of quantum computing is a subfield of quantum information science. It is likely to expand in the next few years as the field shifts toward real-world use in pharmaceutical, data security and other applications.


Quantum cryptography

Quantum cryptography is the science of exploiting quantum mechanical properties to perform cryptographic tasks. The best known example of quantum cryptography is quantum key distribution which offers an information-theoretically secure solution to the key exchange problem. The advantage of quantum cryptography lies in the fact that it allows the completion of various cryptographic tasks that are proven or conjectured to be impossible using only classical (i.e. non-quantum) communication. For example, it is impossible to copy data encoded in a quantum state. If one attempts to read the encoded data, the quantum state will be changed due to wave function collapse (no-cloning theorem). This could be used to detect eavesdropping in quantum key distribution.


Quantum information science

Quantum information science is an interdisciplinary field that seeks to understand the analysis, processing, and transmission of information using quantum mechanics principles. It combines the study of Information science with quantum effects in physics. It includes theoretical issues in computational models and more experimental topics in quantum physics, including what can and cannot be done with quantum information. The term quantum information theory is also used, but it fails to encompass experimental research, and can be confused with a subfield of quantum information science that addresses the processing of quantum information.


Quantum mechanics

Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistry, quantum field theory, quantum technology, and quantum information science.


Quantum optics

Quantum optics is a branch of atomic, molecular, and optical physics dealing with how individual quanta of light, known as photons, interact with atoms and molecules. It includes the study of the particle-like properties of photons. Photons have been used to test many of the counter-intuitive predictions of quantum mechanics, such as entanglement and teleportation, and are a useful resource for quantum information processing.


Quantum technology

Quantum technology is an emerging field of physics and engineering, which relies on the principles of quantum physics. Quantum computing, quantum sensors, quantum cryptography, quantum simulation, quantum metrology and quantum imaging are all examples of quantum technologies, where properties of quantum mechanics, especially quantum entanglement, quantum superposition and quantum tunnelling, are important.


Queen regnant

A queen regnant (plural: queens regnant) is a female monarch, equivalent in rank and title to a king, who reigns in her own right over a realm known as a “kingdom”; as opposed to a queen consort, who is the wife of a reigning king; or a queen regent, who is the guardian of a child monarch and rules temporarily in the child’s stead, be it de jure in sharing power, or de facto in ruling alone. A princess regnant is a female monarch who reigns in her own right over a “principality”; an empress regnant is a female monarch who reigns in her own right over an “empire”.

A queen regnant possesses and exercises sovereign powers, whereas a queen consort or queen regent shares her spouse’s and/or child’s rank and titles, but does not share the sovereignty of her spouse or child. The husband or child of a queen regnant traditionally does not share the queen regnant’s rank, title or sovereignty. However, the concept of a king consort or prince consort is not unheard of in both contemporary and classical periods.

A queen dowager or empress dowager is the widow of a king or emperor; a queen mother is a queen dowager who is also the mother of a reigning sovereign.