Reconstruction of quantum states based on measurements
Quantum tomography or quantum state tomography is the process by which a quantum state is reconstructed using measurements on an ensemble of identical quantum states.[1] The source of these states may be any device or system which prepares quantum states either consistently into quantum pure states or otherwise into general mixed states. To be able to uniquely identify the state, the measurements must be tomographically complete. That is, the measured operators must form an operator basis on the Hilbert space of the system, providing all the information about the state. Such a set of observations is sometimes called a quorum. The term tomography was first used in the quantum physics literature in a 1993 paper introducing experimental optical homodyne tomography.[2]
In quantum process tomography on the other hand, known quantum states are used to probe a quantum process to find out how the process can be described. Similarly, quantum measurement tomography works to find out what measurement is being performed. Whereas, randomized benchmarking scalably obtains a figure of merit of the overlap between the error prone physical quantum process and its ideal counterpart.
The general principle behind quantum state tomography is that by repeatedly performing many different measurements on quantum systems described by identical density matrices, frequency counts can be used to infer probabilities, and these probabilities are combined with Born's rule to determine a density matrix which fits the best with the observations.
This can be easily understood by making a classical analogy. Consider a harmonic oscillator (e.g. a pendulum). The position and momentum of the oscillator at any given point can be measured and therefore the motion can be completely described by the phase space. This is shown in figure 1. By performing this measurement for a large number of identical oscillators we get a probability distribution in the phase space (figure 2). This distribution can be normalized (the oscillator at a given time has to be somewhere) and the distribution must be non-negative. So we have retrieved a function which gives a description of the chance of finding the particle at a given point with a given momentum.
For quantum mechanical particles the same can be done. The only difference is that the Heisenberg's uncertainty principle mustn't be violated, meaning that we cannot measure the particle's momentum and position at the same time. The particle's momentum and its position are called quadratures (see Optical phase space for more information) in quantum related states. By measuring one of the quadratures of a large number of identical quantum states will give us a probability density corresponding to that particular quadrature. This is called the marginal distribution, or (see figure 3). In the following text we will see that this probability density is needed to characterize the particle's quantum state, which is the whole point of quantum tomography.
^Quantum State Tomography. "UIUC".
^Smithey, D. T.; Beck, M.; Raymer, M. G.; Faridani, A. (1993-03-01). "Measurement of the Wigner distribution and the density matrix of a light mode using optical homodyne tomography: Application to squeezed states and the vacuum". Physical Review Letters. 70 (9): 1244–1247. Bibcode:1993PhRvL..70.1244S. doi:10.1103/physrevlett.70.1244. ISSN 0031-9007. PMID 10054327.
and 28 Related for: Quantum tomography information
Quantumtomography or quantum state tomography is the process by which a quantum state is reconstructed using measurements on an ensemble of identical...
materials science, cosmochemistry, astrophysics, quantum information, and other areas of science. The word tomography is derived from Ancient Greek τόμος tomos...
computer.: 317 Quantum state tomography is a process by which, given a set of data representing the results of quantum measurements, a quantum state consistent...
tomography, where a quantum state is learned from measurement. Other applications include learning Hamiltonians and automatically generating quantum experiments...
Permutationally invariant quantum state tomography (PI quantum state tomography) is a method for the partial determination of the state of a quantum system consisting...
Quantum optical coherence tomography (Q-OCT) is an imaging technique that uses nonclassical (quantum) light sources to generate high-resolution images...
L. (1998). "Reconstruction of Quantum States of Spin Systems: From Quantum Bayesian Inference to QuantumTomography". Annals of Physics. 266 (2): 454–496...
This allows quantum experiments to verify that the phonons within the SAW Resonator are in quantum fock states by using Quantumtomography. Similar attempts...
which one it is. This assumption distinguishes such techniques from quantumtomography, which does not impose additional requirements on the state of the...
phenomenon, that can be interpreted as an instance of device-independent quantumtomography, was first pointed out by Tsirelson and named self-testing by Mayers...
study of quantum systems is the focus of an emergent area of physics research. A basic example of this is quantum state tomography, where a quantum state...
Optical coherence tomography (OCT) is an imaging technique that uses interferometry with short-coherence-length light to obtain micrometer-level depth...
Teleportation as a quantum computation Quantum teleportation with atoms: quantum process tomography Entangled State Teleportation Fidelity of quantum teleportation...
amplitude damping channel. Quantumtomography is a process by which, given a set of data representing the results of quantum measurements, a density matrix...
radioligands allowed single-photon emission computed tomography (SPECT) and positron emission tomography (PET) of the brain. More or less concurrently, magnetic...
IBM Quantum Platform (previously known as IBM Quantum Experience) is an online platform allowing public and premium access to cloud-based quantum computing...
addition to classical wave model for understanding optical interference, quantum matter waves also demonstrate interference. The above can be demonstrated...
Quantum imaging is a new sub-field of quantum optics that exploits quantum correlations such as quantum entanglement of the electromagnetic field in order...
imaginary components of the electric field (see coherent state). Quantumtomography Frequency-resolved optical gating The Wigner distribution was the...
For instance, in quantum process tomography, the unknown quantum process is assumed to be a quantum operation. However, not all quantum processes can be...
strong measurements of a complementary variable, were used to perform quantumtomography (i.e. reconstruct the state in which the photons were prepared). Weak...
ionizing radiation, which distinguishes it from computed tomography (CT) and positron emission tomography (PET) scans. MRI is a medical application of nuclear...
Optical tomography is a form of computed tomography that creates a digital volumetric model of an object by reconstructing images made from light transmitted...
required to produce a least-squares fit using even a quantum computer running a quantum state tomography algorithm becomes very large. Wiebe et al. find that...
described in detail by J. A. Panitz in the same year. Modern day atom probe tomography uses a position sensitive detector aka a FIM in a box to deduce the lateral...