No-cloning theorem
The no-cloning theorem is a fundamental principle in quantum mechanics that states it is impossible to create an identical copy (or "clone") of an arbitrary unknown quantum state. This theorem is significant because it highlights a key difference between classical information and quantum information. In classical physics, if you have a piece of information, you can make copies of it easily.
No-communication theorem
The No-communication theorem is a concept in quantum mechanics that pertains to the behavior of entangled particles. It states that quantum entanglement cannot be used to transmit information or communicate faster than the speed of light, even though the measurement of one entangled particle can instantaneously affect the state of another, distant entangled particle.
No-deleting theorem
The No-Deleting Theorem is a concept from computer science, particularly in the context of programming languages and type systems. Specifically, it is most commonly associated with the field of functional programming and the study of certain types of data structures and algorithms.
Noiseless subsystems
Noiseless subsystems (NSS) is a concept in quantum information theory that addresses the challenges of noise in quantum computations and communication. It is particularly relevant for quantum error correction and quantum communication systems. The key idea behind noiseless subsystems is to identify portions of a quantum system that remain unaffected, or "noiseless," under certain types of noise, allowing for effective encoding and processing of quantum information.
Nuclear Magnetic Resonance (NMR) quantum computing is a type of quantum computing that uses the principles of nuclear magnetic resonance to manipulate quantum bits, or qubits. In this approach, the states of qubits are represented by the nuclear spins of atoms (often isotopes like carbon-13, nitrogen-15, or phosphorus-31) within a molecule.
Optical cluster state
An optical cluster state is a type of photonic quantum state that is now being studied for its potential applications in quantum computing and quantum information processing. Cluster states are a particular kind of multi-particle entangled state that can be used to implement measurement-based quantum computation (MBQC), where computations are carried out through a series of measurements performed on entangled states. ### Key Characteristics of Optical Cluster States: 1. **Entanglement**: Optical cluster states are strongly entangled states of photons.
Pauli group
In quantum mechanics and quantum information theory, the Pauli group is a set of important matrices related to the Pauli operators, which play a crucial role in the formulation of quantum gates and quantum error correction. The Pauli group on \( n \) qubits, denoted as \( \mathcal{P}_n \), consists of all \( n \)-qubit operators that can be expressed as the tensor products of the Pauli operators, up to a phase factor.
Phase qubit
A phase qubit is a type of quantum bit (qubit) used in quantum computing that relies on the phase of a superconducting circuit for its encoding of quantum information. Unlike traditional qubits, which may represent states as 0 and 1 based on energy levels (e.g., in a transmon qubit), phase qubits utilize the quantum mechanical property of phase to represent information.
Physical Review A
Physical Review A (PRA) is a peer-reviewed scientific journal that focuses on research in the field of atomic, molecular, and optical physics, as well as quantum information, quantum mechanics, and foundational aspects of these areas. It is one of the journals published by the American Physical Society (APS) and is part of the Physical Review family of journals, which includes other specialized publications such as Physical Review B, Physical Review C, and Physical Review D, each focusing on different aspects of physics.
Pockels effect
The Pockels effect, also known as the linear electro-optic effect, refers to the change in the refractive index of certain materials in response to an applied electric field. This phenomenon occurs in non-centrosymmetric materials, meaning that these materials lack a center of symmetry in their crystal structure. When an electric field is applied to such materials, their dielectric polarization changes, which in turn affects their refractive index.
Pulse programming
Pulse programming generally refers to a type of programming used in the context of quantum computing, specifically in controlling quantum processors. It involves the precise manipulation of quantum bits (qubits) using carefully timed sequences of microwave pulses or other forms of control signals. In more detail: 1. **Quantum Control**: Pulse programming is essential for executing quantum algorithms because it enables the precise control necessary to manipulate qubits accurately.
The Pusey–Barrett–Rudolph (PBR) theorem is a result in quantum mechanics that addresses the interpretation of quantum states and their relationship to physical reality. Proposed by Matthew Pusey, Jonathan Barrett, and Nicolas Rudolph in 2012, the theorem argues against certain interpretations of quantum mechanics, particularly those that claim that quantum states merely represent knowledge about an underlying reality rather than representing a physical reality itself.
Quantinuum
Quantinuum is a technology company focused on quantum computing and quantum technologies. It was formed through the merger of Honeywell's quantum computing division and Cambridge Quantum Computing, a prominent quantum software company. The company aims to advance quantum computing through hardware, software, and algorithms, offering quantum solutions that leverage the unique capabilities of quantum mechanics.
Quantum Byzantine agreement
Quantum Byzantine Agreement (QBA) is a protocol that addresses the Byzantine Generals Problem using quantum communication techniques. The classic Byzantine Generals Problem involves a group of actors (generals) who must agree on a common strategy, even when some of the actors may fail or act maliciously (like sending false messages). This problem is significant in distributed computing and networked systems, where achieving consensus is often challenging due to unreliable participants.
Quantum Communications Hub
The Quantum Communications Hub is typically a research initiative or collaborative project focused on advancing the field of quantum communication technology. These hubs aim to explore and develop new methods of secure communication using the principles of quantum mechanics, such as quantum key distribution (QKD) and entanglement. Key objectives of Quantum Communications Hubs often include: 1. **Research and Development**: Conducting cutting-edge research in quantum technologies to understand and develop quantum communication protocols and systems.
Quantum Cramér–Rao bound
The Quantum Cramér–Rao bound (QCRB) is a fundamental result in quantum estimation theory. It generalizes the classical Cramér-Rao bound to the realm of quantum mechanics, providing a theoretical lower limit on the variance of unbiased estimators for quantum parameters. ### Key Concepts: 1. **Parameter Estimation**: In quantum mechanics, one often wishes to estimate parameters (like phase, frequency, etc.) of quantum states.
Quantum Experiments at Space Scale, often abbreviated as QUESS, refers to scientific endeavors aimed at conducting quantum mechanics experiments that leverage the unique conditions provided by space, such as microgravity and the ability to control environments over vast distances. One of the most notable projects associated with this concept is the Chinese satellite mission called Micius, launched in 2016 as part of the QUESS project.
Quantum Fisher information
Quantum Fisher Information (QFI) is a fundamental concept in quantum estimation theory, which quantifies the amount of information that an observable quantum state provides about a parameter of interest. It plays a crucial role in tasks such as quantum parameter estimation, quantum metrology, and quantum state discrimination.
Quantum LC circuit
A Quantum LC circuit is a type of quantum circuit that is based on the principles of quantum mechanics and utilizes the properties of inductance (L) and capacitance (C) to create electrical circuits that can exhibit quantum behaviors. The "LC" in the name refers to the combination of inductors (L) and capacitors (C) that form resonant circuits.
Quantum Markov chain
A Quantum Markov chain is an extension of classical Markov chains to the realm of quantum mechanics. Just as classical Markov chains model systems that evolve probabilistically over time, quantum Markov chains aim to capture the dynamics of quantum states as they evolve, potentially influenced by measurements and interactions with environments or other quantum systems.