Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:1308.5650 · Physical Review Letters

Beyond Spectral Homodyne Detection: Complete Quantum Measurement of Spectral Modes of Light

F. A. S. Barbosa, A. S. Coelho, K. N. Cassemiro, P. Nussenzveig, Claude Fabre, M. Martinelli, Alessandro S. Villar

Published Nov 14, 2013• 42 citations
arXivHTMLPDF

Abstract

Spectral homodyne detection, a widely used technique for measuring quantum properties of light beams, cannot retrieve all the information needed to reconstruct the quantum state of spectral field modes. We show that full quantum state reconstruction can be achieved with the alternative measurement technique of resonator detection. We experimentally demonstrate this difference by engineering a quantum state with features that go undetected by homodyne detection but are clearly revealed by resonator detection.

DOI
10.1103/physrevlett.111.200402

Related papers

Quantum state reconstruction of spectral field modes: Homodyne and resonator detection schemes

F. A. S. Barbosa, A. S. Coelho, K. N. Cassemiro +4 more

We revisit the problem of quantum state reconstruction of light beams from the photocurrent quantum noise. As is well known, but often overlooked, two longitudinal field modes contribute to each spectral component of the photocurrent (sideband modes). We show that spectral homodyne detection is intrinsically incapable of providing all the information needed for the full reconstruction of the two-mode spectral quantum state. Such a limitation is overcome by the technique of resonator detection. A detailed theoretical description and comparison of both methods is presented, as well as an experiment to measure the six-mode quantum state of pump-signal-idler beams of an optical parametric oscillator above the oscillation threshold.

arXiv:1310.2427•Physical Review A•Nov 14, 2013•45 citations

Assumption-free measurement of the quantum state of light: Exploring the sidebands of intense fields

F. A. S. Barbosa, A. S. Coelho, K. N. Cassemiro +3 more

The quantum noise in photocurrent fluctuations usually gives incomplete information about the quantum state of spectral sideband modes of bright light beams involved in the detection. Each frequency component of the noise spectrum corresponds to two sideband modes symmetrically located around the bright optical field. In the case of the usual homodyne detection, it limits the ability to recover discriminated information of each mode involved. We theoretically show that complete reconstruction of the two-mode quantum state can be obtained by using phase-locked (coherent) resonator detection, even for non-Gaussian states. We experimentally demonstrate the technique by measuring a two-mode displaced coherent state.

Physical Review A•Dec 7, 2020•9 citations

Uncovering Hidden Entanglement in Twin Beams

R. L. Rincón Celis, Gaurav Nirala, A. Montaña Guerrero +5 more

Proper characterization of quantum correlations in multimode optical quantum states is critical for applications in quantum information science. However, standard entanglement measurements can lead to incomplete state reconstruction and characterization. Here, we implement a resonator-based detection system that reveals entanglement between sideband modes of twin beams, achieving full tomography and retrieving often ignored quantum correlations. Unlike standard spectral measurements such as homodyne detection, resonator detection can independently address the sidebands of each beam, thereby accessing these hidden correlations. Additionally, we show how phase shifts between the carrier and the sideband modes of the involved fields redistribute information and modify the observation of entanglement for different witnesses. The ability of the resonant detection to independently address sideband modes of entangled states can contribute to enhancing the capacity for secure communication and quantum networking protocols.

Physical Review Letters•Jul 16, 2026•0 citations

Phase coherent resonator detection as a complete quantum measurement of the two-mode spectral quantum state of light

F. A. S. Barbosa, A. S. Coelho, K. N. Cassemiro +3 more

The introduction of phase coherence in the detection of quantum noise of light yields a pure quantum measurement of spectral modes. We theoretically show that such coherent quantum measurement performed with the technique of resonator detection (RD) is able to access any direction in the two-mode phase space of spectral sidebands under appropriate conditions, thus furnishing a complete measurement of the four-dimensional Wigner function. We obtain a realistic measurement operator for coherent RD by including the effects of imperfect resonator mode matching in our analysis. Moreover, we experimentally demonstrate the realization of phase coherent RD to characterize a two-mode displaced quantum state.

arXiv:1512.06096•Dec 18, 2015•0 citations

Spectrally-resolved, DC-balanced homodyne detection for ultrafast, multimode quantum field state measurement

Ian A. Walmsley, Chris Iaconis

Ultimately the properties of all optical fields are contained in the density matrix that specifies their quantum mechanical state. It has only recently been demonstrated that it is possible to actually reconstruct this density matrix from measured data, and to do so with temporal resolution of a few hundred femtoseconds.[1] This technique, known as Optical Homodyne Tomography (OHT), is unfortunately restricted to the measurement of only single mode radiation. In fact it selects out from the test field only those components which overlap temporally with the local oscillator pulse mode.

International Conference on Ultrafast Phenomena•Jan 1, 1996•0 citations

From spectral matrix to sideband structure: exploring stereo multimodes

M. Martinelli

We recall the details involving the generation of light beams by optical cavities in order to explore the quantum properties that are revealed from the covariance matrices of the quadratures of the fields. This consideration is necessary to reveal the structure involving the sidebands of the resonant cavity modes, their reconstruction from the linearized Hamiltonian, and the fact that, for each output beam generated from an optical cavity observed under a defined electronic analysis frequency, we access a double space of modes involving the sidebands. The full measurement of those sidebands is revisited, and the distinct techniques are compared, showing their advantages, drawbacks, and perspectives.

Journal of the Optical Society of America B•Apr 3, 2023•3 citations
Spectral homodyne detection, a widely used technique for measuring quantum properties of light beams, cannot retrieve all the information needed to reconstruct the quantum state of spectral field modes. We show that full quantum state reconstruction can be achieved with the alternative measurement technique of resonator detection. We experimentally demonstrate this difference by engineering a quantum state with features that go undetected by homodyne detection but are clearly revealed by resonator detection.
We revisit the problem of quantum state reconstruction of light beams from the photocurrent quantum noise. As is well known, but often overlooked, two longitudinal field modes contribute to each spectral component of the photocurrent (sideband modes). We show that spectral homodyne detection is intrinsically incapable of providing all the information needed for the full reconstruction of the two-mode spectral quantum state. Such a limitation is overcome by the technique of resonator detection. A detailed theoretical description and comparison of both methods is presented, as well as an experiment to measure the six-mode quantum state of pump-signal-idler beams of an optical parametric oscillator above the oscillation threshold.
The quantum noise in photocurrent fluctuations usually gives incomplete information about the quantum state of spectral sideband modes of bright light beams involved in the detection. Each frequency component of the noise spectrum corresponds to two sideband modes symmetrically located around the bright optical field. In the case of the usual homodyne detection, it limits the ability to recover discriminated information of each mode involved. We theoretically show that complete reconstruction of the two-mode quantum state can be obtained by using phase-locked (coherent) resonator detection, even for non-Gaussian states. We experimentally demonstrate the technique by measuring a two-mode displaced coherent state.
Proper characterization of quantum correlations in multimode optical quantum states is critical for applications in quantum information science. However, standard entanglement measurements can lead to incomplete state reconstruction and characterization. Here, we implement a resonator-based detection system that reveals entanglement between sideband modes of twin beams, achieving full tomography and retrieving often ignored quantum correlations. Unlike standard spectral measurements such as homodyne detection, resonator detection can independently address the sidebands of each beam, thereby accessing these hidden correlations. Additionally, we show how phase shifts between the carrier and the sideband modes of the involved fields redistribute information and modify the observation of entanglement for different witnesses. The ability of the resonant detection to independently address sideband modes of entangled states can contribute to enhancing the capacity for secure communication and quantum networking protocols.
The introduction of phase coherence in the detection of quantum noise of light yields a pure quantum measurement of spectral modes. We theoretically show that such coherent quantum measurement performed with the technique of resonator detection (RD) is able to access any direction in the two-mode phase space of spectral sidebands under appropriate conditions, thus furnishing a complete measurement of the four-dimensional Wigner function. We obtain a realistic measurement operator for coherent RD by including the effects of imperfect resonator mode matching in our analysis. Moreover, we experimentally demonstrate the realization of phase coherent RD to characterize a two-mode displaced quantum state.
Ultimately the properties of all optical fields are contained in the density matrix that specifies their quantum mechanical state. It has only recently been demonstrated that it is possible to actually reconstruct this density matrix from measured data, and to do so with temporal resolution of a few hundred femtoseconds.[1] This technique, known as Optical Homodyne Tomography (OHT), is unfortunately restricted to the measurement of only single mode radiation. In fact it selects out from the test field only those components which overlap temporally with the local oscillator pulse mode.
We recall the details involving the generation of light beams by optical cavities in order to explore the quantum properties that are revealed from the covariance matrices of the quadratures of the fields. This consideration is necessary to reveal the structure involving the sidebands of the resonant cavity modes, their reconstruction from the linearized Hamiltonian, and the fact that, for each output beam generated from an optical cavity observed under a defined electronic analysis frequency, we access a double space of modes involving the sidebands. The full measurement of those sidebands is revisited, and the distinct techniques are compared, showing their advantages, drawbacks, and perspectives.