<div dir="ltr">All,<div><br></div><div>For any of you who viewed last Wednesday's talk on the EHT introduced by Young's 1801 "Double Slit Interference Experiment" </div><div><br></div><div>Wolfgang Kettle's Group at MIT offers perhaps the ultimate distillation -- down to the atomic level: </div><div><br></div><div>The MIT News reports:</div><div><br></div><div><div id="gmail-block-mit-page-title" style="color:rgb(5,5,5);font-family:MessinaSans,sans-serif"><div class="gmail-block-inner" style=""><h1 style="margin:0px 0px 7px;line-height:1.05;letter-spacing:-0.035em;color:rgb(51,51,51);width:884.393px"><font size="4">Famous double-slit experiment holds up when stripped to its quantum essentials</font></h1></div></div><div id="gmail-block-mit-content" style=""><div class="gmail-block-inner" style=""><div class="gmail-news-article--dek" style="margin-bottom:20px;width:884.393px;color:rgb(51,51,51)"><font size="4" style="">MIT physicists confirm that, like Superman, light has two identities that are impossible to see at once.</font></div><div class="gmail-news-article--indicators" style="font-size:20px"></div><div class="gmail-news-article--authored-by" style="margin:0px 0px 5px;width:884.393px;color:rgb(51,51,51)"><span class="gmail-news-article--author" style="">Jennifer Chu</span> <span class="gmail-news-article--authored-by--separator" style="color:rgb(62,62,62)">|</span> <span class="gmail-news-article--source" style="">MIT News</span></div><div class="gmail-news-article--publication-date" style="margin:4px 0px 30px;width:884.393px;color:rgb(51,51,51)"><div class="gmail-visually-hidden" style="border:0px;height:1px;overflow:hidden;padding:0px;width:1px;color:rgb(5,5,5)"><span class="gmail-label">Publication Date</span><span class="gmail-visually-hidden" style="border:0px;height:1px;overflow:hidden;padding:0px;width:1px">:</span></div>July 28, 2025</div><div class="gmail-news-article--publication-date" style="margin:4px 0px 30px;font-weight:700;width:884.393px;color:rgb(51,51,51)"><img src="cid:ii_mdoyjr1j0" alt="image.png" width="188" height="158" style="margin-right: 0px;"> </div><div class="gmail-news-article--publication-date" style="margin:4px 0px 30px;font-weight:700;width:884.393px;color:rgb(51,51,51)"><span style="font-weight:400">What we have done can be regarded as a new variant to the double-slit experiment,” Wolfgang Ketterle says, pictured with members of the MIT team. Front, left to right: Yoo Kyung Lee and Hanzhen Lin. Back: Jiahao Lyu, Yu-Kun Lu, Wolfgang Ketterle, and Vitaly Fedoseev.</span><br style="font-weight:400"><span style="font-weight:400">Credits:Credit: Courtesy of the researchers</span></div><img src="cid:ii_mdoykzvw1" alt="image.png" width="188" height="126" style="margin-right: 0px;"><div class="gmail-news-article--media--image--caption" style="color:rgb(5,5,5);font-family:MessinaSans,sans-serif">Schematic of the MIT experiment: Two single atoms floating in a vacuum chamber are illuminated by a laser beam and act as the two slits. The interference of the scattered light is recorded with a highly sensitive camera depicted as a screen. Incoherent light appears as background and implies that the photon has acted as a particle passing only through one slit.</div><div class="gmail-news-article--media--image--credits" style="color:rgb(5,5,5);font-family:MessinaSans,sans-serif;margin-top:9px"><div class="gmail-visually-hidden" style="border:0px;height:1px;overflow:hidden;padding:0px;width:1px"><span class="gmail-label">Credits</span><span class="gmail-visually-hidden" style="border:0px;height:1px;overflow:hidden;padding:0px;width:1px">:</span></div>Credit: Courtesy of the researchers</div><div class="gmail-news-article--media--image--credits" style="color:rgb(5,5,5);font-family:MessinaSans,sans-serif;margin-top:9px"><br></div><div class="gmail-news-article--publication-date" style="color:rgb(51,51,51);font-family:MessinaSans,sans-serif;margin:4px 0px 30px;font-weight:700;width:884.393px"><p class="MsoNormal" style="margin:0in;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif;color:rgb(34,34,34);background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial">All,</span><span style="font-family:"Times New Roman",serif"></span></p>
<p class="MsoNormal" style="margin:0in;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif;color:rgb(34,34,34)"> </span></p>
<p class="MsoNormal" style="margin:0in;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif;color:rgb(34,34,34)">For any of you who
viewed last Wednesday's talk on the EHT introduced by Young's 1801 "Double
Slit Interference Experiment" </span></p>
<p class="MsoNormal" style="margin:0in;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif;color:rgb(34,34,34)"> </span></p>
<p class="MsoNormal" style="margin:0in;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif;color:rgb(34,34,34)">Wolfgang Kettle's Group
at MIT offers perhaps the ultimate distillation </span></p>
<p class="MsoNormal" style="margin:0in;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif;color:rgb(34,34,34)"> </span></p>
<p class="MsoNormal" style="margin:0in;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif;color:rgb(34,34,34)">The MIT News reports:</span></p>
<p class="MsoNormal" style="margin:0in;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif;color:rgb(34,34,34)"> </span></p>
<p class="MsoNormal" style="margin:0in 0in 5.25pt;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><b><span style="font-size:13.5pt;font-family:Arial,sans-serif;letter-spacing:-0.4pt">Famous double-slit experiment holds up when stripped to its
quantum essentials</span></b><b><span style="font-size:24pt;font-family:Arial,sans-serif;letter-spacing:-0.4pt"></span></b></p>
<p class="MsoNormal" style="line-height:normal;margin:0in 0in 8pt;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-size:13.5pt;font-family:Arial,sans-serif">MIT physicists confirm
that, like Superman, light has two identities that are impossible to see at
once.</span><span style="font-family:Arial,sans-serif"></span></p>
<p class="MsoNormal" style="margin:0in 0in 3.75pt;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif">Jennifer Chu </span><span style="font-family:Arial,sans-serif;color:rgb(62,62,62)">|</span><span style="font-family:Arial,sans-serif"> MIT News</span></p>
<p class="MsoNormal" style="margin:0in;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif;color:rgb(5,5,5)">Publication Date<span style="border:1pt none windowtext;padding:0in">:</span></span></p>
<p class="MsoNormal" style="line-height:normal;margin:0in 0in 8pt;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif">July 28, 2025</span></p>
<p class="MsoNormal" style="line-height:normal;margin:0in 0in 8pt;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif"> </span></p>
<p class="MsoNormal" style="line-height:normal;margin:0in 0in 8pt;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif">What we have done can be regarded as a new variant to the
double-slit experiment,” Wolfgang Ketterle says, pictured with members of the
MIT team. Front, left to right: Yoo Kyung Lee and Hanzhen Lin. Back: Jiahao
Lyu, Yu-Kun Lu, Wolfgang Ketterle, and Vitaly Fedoseev.<br>
Credits: Courtesy of the researchers</span></p>
<p class="MsoNormal" style="margin:0in;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif;color:rgb(5,5,5)">Schematic of the MIT
experiment: Two single atoms floating in a vacuum chamber are illuminated by a
laser beam and act as the two slits. The interference of the scattered light is
recorded with a highly sensitive camera depicted as a screen. Incoherent light
appears as background and implies that the photon has acted as a particle
passing only through one slit.</span><span style="font-family:Arial,sans-serif;color:rgb(34,34,34)"></span></p>
<p class="MsoNormal" style="margin:0in;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif;color:rgb(5,5,5)">Credits<span style="border:1pt none windowtext;padding:0in">:</span> Courtesy of the researchers</span></p>
<p class="MsoNormal" style="margin:0in;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif;color:rgb(5,5,5)"> </span></p>
<p class="MsoNormal" style="line-height:normal;margin:0in 0in 8pt;font-size:12pt;font-family:Aptos,sans-serif"><b><span style="font-family:Arial,sans-serif"></span></b><span style="font-family:Arial,sans-serif;color:rgb(5,5,5)">MIT physicists have performed an idealized version of one
of the most famous experiments in quantum physics. Their findings demonstrate,
with atomic-level precision, the dual yet evasive nature of light. They also
happen to confirm that Albert Einstein was wrong about this particular quantum
scenario.</span><b><span style="font-family:Arial,sans-serif"></span></b></p>
<p class="MsoNormal" style="line-height:normal;margin:0in 0in 8pt;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif;color:rgb(5,5,5)">The experiment in question is the <a href="https://en.wikipedia.org/wiki/Double-slit_experiment" target="_blank" style="color:rgb(70,120,134)"><span style="color:rgb(5,5,5)">double-slit experiment</span></a>, which was first
performed in 1801 by the British scholar Thomas Young to show how light behaves
as a wave. Today, with the formulation of quantum mechanics, the double-slit
experiment is now known for its surprisingly simple demonstration of a head-scratching
reality: that light exists as both a particle and a wave. Stranger still, this
duality cannot be simultaneously observed. Seeing light in the form of
particles instantly obscures its wave-like nature, and vice versa.</span><b><span style="font-family:Arial,sans-serif"></span></b></p>
<p class="MsoNormal" style="margin:0in;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif;color:rgb(34,34,34)">The original experiment
involved shining a beam of light through two parallel slits in a screen and
observing the pattern that formed on a second, faraway screen. One might expect
to see two overlapping spots of light, which would imply that light exists as
particles, a.k.a. photons, like paintballs that follow a direct path. But
instead, the light produces alternating bright and dark stripes on the screen,
in an interference pattern similar to what happens when two ripples in a pond
meet. This suggests light behaves as a wave. Even weirder, when one tries to
measure which slit the light is traveling through, the light suddenly behaves
as particles and the interference pattern disappears...</span></p>
<p class="MsoNormal" style="margin:0in;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif;color:rgb(34,34,34)">Nearly a century ago,
the experiment was at the center of a friendly debate between physicists Albert
Einstein and Niels Bohr. In 1927, Einstein argued that a photon particle should
pass through just one of the two slits and in the process generate a slight
force on that slit, like a bird rustling a leaf as it flies by. He proposed
that one could detect such a force while also observing an interference
pattern, thereby catching light’s particle and wave nature at the same time. In
response, Bohr applied the quantum mechanical uncertainty principle and showed
that the detection of the photon’s path would wash out the interference
pattern.</span></p>
<p class="MsoNormal" style="margin:0in;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif;color:rgb(34,34,34)"> </span></p>
<p class="MsoNormal" style="margin:0in;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif;color:rgb(34,34,34)">Scientists have since
carried out multiple versions of the double-slit experiment, and they have all,
to various degrees, confirmed the validity of the quantum theory formulated by
Bohr. Now, MIT physicists have performed the most “idealized” version of the
double-slit experiment to date. Their version strips down the experiment to its
quantum essentials. They used individual atoms as slits, and used weak beams of
light so that each atom scattered at most one photon. By preparing the atoms in
different quantum states, they were able to modify what information the atoms
obtained about the path of the photons. The researchers thus confirmed the
predictions of quantum theory: The more information was obtained about the path
(i.e. the particle nature) of light, the lower the visibility of the
interference pattern was.</span></p>
<p class="MsoNormal" style="margin:0in;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-size:13pt;font-family:Arial,sans-serif;color:rgb(5,5,5)"> </span></p>
<p class="MsoNormal" style="margin:0in;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-size:13pt;font-family:Arial,sans-serif;color:rgb(5,5,5)"> </span></p>
<p class="MsoNormal" style="margin:0in;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif;color:rgb(34,34,34)">Note that there is a
more physicist like report available [but you might have to purchase it from
AIP]:</span></p>
<div style="border:1pt solid windowtext;padding:0in;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial">
<p class="MsoNormal" style="line-height:24pt;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial;border:none;padding:0in;margin:0in 0in 8pt;font-size:12pt;font-family:Aptos,sans-serif"><b><span style="font-family:"Noto Sans",sans-serif;color:black">Coherent and Incoherent
Light Scattering by Single-Atom Wave Packets</span></b></p>
<p class="MsoNormal" style="margin:0in;line-height:normal;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial;border:none;padding:0in;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-size:11pt;font-family:"Noto Sans",sans-serif;color:black"><a href="https://journals.aps.org/search/field/author/Vitaly%20Fedoseev" style="color:rgb(70,120,134)"><span style="color:rgb(0,83,139);border:1pt solid rgb(0,83,139);padding:0in">Vitaly Fedoseev</span></a><sup><span style="border:1pt solid windowtext;padding:0in">*</span></sup>, <a href="https://journals.aps.org/search/field/author/Hanzhen%20Lin%20%E6%9E%97%E7%BF%B0%E6%A1%A2" style="color:rgb(70,120,134)"><span style="color:rgb(0,83,139);border:1pt solid rgb(0,83,139);padding:0in">Hanzhen Lin (</span><span style="font-family:"MS Gothic";color:rgb(0,83,139);border:1pt solid rgb(0,83,139);padding:0in">林翰</span><span style="font-family:"Microsoft JhengHei",sans-serif;color:rgb(0,83,139);border:1pt solid rgb(0,83,139);padding:0in">桢</span><span style="color:rgb(0,83,139);border:1pt solid rgb(0,83,139);padding:0in">)</span></a><sup><span style="border:1pt solid windowtext;padding:0in">*</span></sup>, <a href="https://journals.aps.org/search/field/author/Yu-Kun%20Lu" style="color:rgb(70,120,134)"><span style="color:rgb(0,83,139);border:1pt solid rgb(0,83,139);padding:0in">Yu-Kun Lu</span></a><sup><span style="border:1pt solid windowtext;padding:0in">*</span></sup>, <a href="https://journals.aps.org/search/field/author/Yoo%20Kyung%20Lee" style="color:rgb(70,120,134)"><span style="color:rgb(0,83,139);border:1pt solid rgb(0,83,139);padding:0in">Yoo Kyung Lee</span></a><sup><span style="border:1pt solid windowtext;padding:0in">*</span></sup>, <a href="https://journals.aps.org/search/field/author/Jiahao%20Lyu" style="color:rgb(70,120,134)"><span style="color:rgb(0,83,139);border:1pt solid rgb(0,83,139);padding:0in">Jiahao Lyu</span></a><sup><span style="border:1pt solid windowtext;padding:0in">*</span></sup>, and <a href="https://journals.aps.org/search/field/author/Wolfgang%20Ketterle" style="color:rgb(70,120,134)"><span style="color:rgb(0,83,139);border:1pt solid rgb(0,83,139);padding:0in">Wolfgang Ketterle</span></a></span></p>
<p class="MsoNormal" style="margin:0in;line-height:95%;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial;border:none;padding:0in;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-size:10pt;line-height:95%;font-family:"Noto Sans",sans-serif;color:black">Phys. Rev. Lett. <span style="border:1pt solid windowtext;padding:0in">135</span>, 043601 – <span style="border:1pt solid windowtext;padding:0in">Published 22 July, 2025</span></span><span style="font-family:"Noto Sans",sans-serif;color:black"></span></p>
<p class="MsoNormal" style="margin:0in;line-height:15pt;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial;border:none;padding:0in;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-size:9pt;font-family:"Noto Sans",sans-serif;color:black;border:1pt solid windowtext;padding:0in">DOI: <a href="https://doi.org/10.1103/zwhd-1k2t" style="color:rgb(70,120,134)">https://doi.org/10.1103/zwhd-1k2t</a></span><a name="abstract"></a><span style="font-size:10.5pt;font-family:"Noto Sans",sans-serif;color:black;border:1pt solid windowtext;padding:0in"></span></p>
<p class="MsoNormal" style="margin:0in;line-height:21pt;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial;border:none;padding:0in;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:"Noto Sans",sans-serif;color:rgb(29,30,39)">Abstract</span></p>
<p class="MsoNormal" style="margin:0in;line-height:95%;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial;border:none;padding:0in;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:"Noto Sans",sans-serif;color:black">We study
light scattering of atomic wave packets in free space and discuss the results
in terms of atom-photon entanglement and which-way information. Using ultracold
atoms released from an optical lattice, we realize a Gedanken experiment which
interferes single photons scattering off of Heisenberg uncertainty-limited wave
packets. We unify the free-space and trapped-atom pictures by measuring the
light scattered before and during wave packet expansion and show the coherence
properties of the scattered light are independent of the presence of the trap.
Therefore, recoilless scattering in a trap (Mössbauer effect), the different
frequency of sidebands, and the excitation of an excited harmonic oscillator
state are not essential to the question of which fraction of light scattering
is coherent or incoherent. Our experiment demonstrates the potential of using
atomic Mott insulators to create single-atom wave packets for fundamental
studies.</span></p>
</div>
<p class="MsoNormal" style="margin:0in;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif;color:rgb(34,34,34)"> </span></p>
<p class="MsoNormal" style="margin:0in;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif;color:rgb(34,34,34)">Alternative version
available without a paywall [may not be identical [but then that’s the qm
aspect]:</span></p>
<p class="MsoNormal" style="margin:0in;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif;color:rgb(34,34,34)"><a href="https://arxiv.org/abs/2410.19671" style="color:rgb(70,120,134)">https://arxiv.org/abs/2410.19671</a></span></p>
<p class="MsoNormal" style="margin:0in;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif;color:rgb(34,34,34)"> </span></p>
<p class="MsoNormal" style="margin:0in;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif;color:rgb(34,34,34)">Anyway – this will be
included in the material to be sent to LCTG to accompany the talk</span></p>
<p class="MsoNormal" style="margin:0in;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif;color:rgb(34,34,34)"> </span></p>
<p class="MsoNormal" style="margin:0in;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif;color:rgb(34,34,34)">Ted</span></p>
<p class="MsoNormal" style="margin:0in;line-height:normal;font-size:12pt;font-family:Aptos,sans-serif"><span style="font-family:Arial,sans-serif;color:rgb(34,34,34)"><a href="https://news.mit.edu/2025/famous-double-slit-experiment-holds-when-stripped-to-quantum-essentials-0728" style="color:rgb(70,120,134)">https://news.mit.edu/2025/famous-double-slit-experiment-holds-when-stripped-to-quantum-essentials-0728</a></span></p></div></div></div></div><div><br></div><div><br></div><div><br></div></div>