[HN Gopher] Interferometric imaging of amplitude and phase of sp...
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       Interferometric imaging of amplitude and phase of spatial biphoton
       states
        
       Author : lnyan
       Score  : 7 points
       Date   : 2023-08-23 06:19 UTC (16 hours ago)
        
 (HTM) web link (www.nature.com)
 (TXT) w3m dump (www.nature.com)
        
       | westurner wrote:
       | From "Interferometric imaging of amplitude and phase of spatial
       | biphoton states" (2023)
       | https://www.nature.com/articles/s41566-023-01272-3 :
       | 
       | > [...] _The number of projective measurements necessary for a
       | full-state tomography scales quadratically with the
       | dimensionality of the Hilbert space under consideration [2]. This
       | issue can be tackled with adaptive tomographic approaches [3,4,5]
       | or compressive techniques [6,7], which are, however, constrained
       | by a priori hypotheses on the quantum state under study.
       | Moreover, quantum state tomography via projective measurement
       | becomes challenging when the dimension of the quantum state is
       | not a power of a prime number [8]. Here we try to tackle the
       | tomographic challenge, in the specific contest of spatially
       | correlated biphoton states, looking for an interferometric
       | approach inspired by digital holography [9,10,11], familiar in
       | classical optics. We show that the coincidence imaging of the
       | superposition of two biphoton states, one unknown and one used as
       | a reference state, allows retrieving the spatial distribution of
       | phase and amplitude of the unknown biphoton wavefunction.
       | Coincidence imaging can be achieved with_ [... Quantum Imaging]
        
         | westurner wrote:
         | From "Physicists use a 350-year-old theorem to reveal new
         | properties of light waves" (yesterday, 2023)
         | https://news.ycombinator.com/item?id=37226121 :
         | 
         | >> _proves for the first time that a light wave 's degree of
         | non-quantum entanglement exists in a direct and complementary
         | relationship with its degree of polarization. As one rises, the
         | other falls, enabling the level of entanglement to be inferred
         | directly from the level of polarization, and vice versa. This
         | means that hard-to-measure optical properties such as
         | amplitudes, phases and correlations--perhaps even these of
         | quantum wave systems--can be deduced from something a lot
         | easier to measure: light intensity_
        
       | [deleted]
        
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