83 citations · 475 across the 27 of their papers we have counts for
23 papers · 1 filter
Determining quantum coherence with minimal resources
Claudio Carmeli, Teiko Heinosaari, Sabrina Maniscalco +2
We characterize minimal measurement setups for validating the quantum coherence of an unknown quantum state. We show that for a -level system, the optimal strategy consists of m…
Number and phase: complementarity and joint measurement uncertainties
Pekka Lahti, Juha-Pekka Pellonpää, Jussi Schultz
We show that number and canonical phase (of a single mode optical field) are complementary observables. We also bound the measurement uncertainty region for their approximate joint…
Probing quantum state space: does one have to learn everything to learn something?
Claudio Carmeli, Teiko Heinosaari, Jussi Schultz +1
Determining the state of a quantum system is a consuming procedure. For this reason, whenever one is interested only in some particular property of a state, it would be desirable t…
Quantum incompatibility in collective measurements
Claudio Carmeli, Teiko Heinosaari, Daniel Reitzner +2
We study the compatibility (or joint measurability) of quantum observables in a setting where the experimenter has access to multiple copies of a given quantum system, rather than…
Efficient Pure State Quantum Tomography from Five Orthonormal Bases
Claudio Carmeli, Teiko Heinosaari, Michael Kech +2
For any finite dimensional Hilbert space, we construct explicitly five orthonormal bases such that the corresponding measurements allow for efficient tomography of an arbitrary pur…
Verifying the quantumness of bipartite correlations
Claudio Carmeli, Teiko Heinosaari, Antti Karlsson +2
Entanglement is at the heart of most quantum information tasks, and therefore considerable effort has been made to find methods of deciding the entanglement content of a given bipa…
Breaking Gaussian incompatibility on continuous variable quantum systems
Teiko Heinosaari, Jukka Kiukas, Jussi Schultz
We characterise Gaussian quantum channels that are Gaussian incompatibility breaking, that is, transform every set of Gaussian measurements into a set obtainable from a joint Gauss…
Incompatibility breaking quantum channels
Teiko Heinosaari, Jukka Kiukas, Daniel Reitzner +1
A typical bipartite quantum protocol, such as EPR-steering, relies on two quantum features, entanglement of states and incompatibility of measurements. Noise can delete both of the…
How many orthonormal bases are needed to distinguish all pure quantum states?
Claudio Carmeli, Teiko Heinosaari, Jussi Schultz +1
We collect some recent results that together provide an almost complete answer to the question stated in the title. For the dimension d=2 the answer is three. For the dimensions d=…
Expanding the principle of local distinguishability
Claudio Carmeli, Teiko Heinosaari, Jussi Schultz +1
The principle of local distinguishability states that an arbitrary physical state of a bipartite system can be determined by the combined statistics of local measurements performed…
Maximally incompatible quantum observables
Teiko Heinosaari, Jussi Schultz, Alessandro Toigo +1
The existence of maximally incompatible quantum observables in the sense of a minimal joint measurability region is investigated. Employing the universal quantum cloning device it…
Informationally complete sets of Gaussian measurements
Jukka Kiukas, Jussi Schultz
We prove necessary and sufficient conditions for the informational completeness of an arbitrary set of Gaussian observables on continuous variable systems with finite number of deg…
Tasks and premises in quantum state determination
Claudio Carmeli, Teiko Heinosaari, Jussi Schultz +1
The purpose of quantum tomography is to determine an unknown quantum state from measurement outcome statistics. There are two obvious ways to generalize this setting. First, our ta…
On measurements of the canonical phase observable
Juha-Pekka Pellonpää, Jussi Schultz
Measurements of single-mode phase observables are studied in the spirit of the quantum theory of measurement. We determine the minimal measurement models of phase observables and c…
Comparing the degrees of incompatibility inherent in probabilistic physical theories
Paul Busch, Teiko Heinosaari, Jussi Schultz +1
We introduce a new way of quantifying the degrees of incompatibility of two ob- servables in a probabilistic physical theory and, based on this, a global measure of the degree of i…
A note on the Pauli problem in light of approximate joint measurements
Jussi Schultz
We show that there exist informationally incomplete phase space observables such that the Cartesian margins are informationally equivalent with position and momentum. This shows th…
Weak vs. approximate values in quantum state determination
Erkka Haapasalo, Pekka Lahti, Jussi Schultz
We generalize the concept of a weak value of a quantum observable to cover arbitrary real positive operator measures. We show that the definition is operationally meaningful in the…
Balancing efficiencies by squeezing in realistic eight-port homodyne detection
Juha-Pekka Pellonpää, Jussi Schultz, Matteo G. A. Paris
We address measurements of covariant phase observables (CPOs) by means of realistic eight-port homodyne detectors. We do not assume equal quantum efficiencies for the four photodet…
Tilted phase space measurements
Pekka Lahti, Jussi Schultz
We show that the phase shift of π/2 is crucial for the phase space translation covariance of the measured high-amplitude limit observable in eight-port homodyne detection. However,…
Inefficient eight-port homodyne detection and covariant phase space observables
Pekka Lahti, Juha-Pekka Pellonpää, Jussi Schultz
We consider the quantum optical eight-port homodyne detection scheme in the case that each of the associated photon detectors is assigned with a different quantum efficiency. We gi…
Density matrix reconstruction from displaced photon number distributions
Jukka Kiukas, Juha-Pekka Pellonpää, Jussi Schultz
We consider state reconstruction from the measurement statistics of phase space observables generated by photon number states. The results are obtained by inverting certain infinit…
State reconstruction formulas for the s-distributions and quadratures
Jukka Kiukas, Juha-Pekka Pellonpää, Jussi Schultz
We consider the method of infinite matrix inversion in the context of quantum state reconstruction. Using this method we give rigorous proofs for reconstruction formulas for the Ca…
Position and momentum tomography
Jukka Kiukas, Pekka Lahti, Jussi Schultz
We illustrate the use of the statistical method of moments for determining the position and momentum distributions of a quantum object from the statistics of a single measurement.…