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<p class="MsoNormal"><i><span style="font-size:12.0pt;font-family:Helvetica;color:#8B0102">UNIVERSITY OF CHICAGO</span></i><o:p></o:p></p>
<p class="MsoNormal"><i><span style="font-size:12.0pt;font-family:Helvetica;color:#8B0102">COMPUTER SCIENCE DEPARTMENT</span></i><o:p></o:p></p>
<p class="MsoNormal"><i><span style="font-size:12.0pt;font-family:Helvetica;color:#8B0102">PRESENTS</span></i><o:p></o:p></p>
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<p class="MsoNormal"><b><span style="font-size:14.0pt;font-family:Helvetica">Ray Li</span></b><o:p></o:p></p>
<p class="MsoNormal"><b><span style="font-size:14.0pt;font-family:Helvetica">University of Santa Clara</span></b><o:p></o:p></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;color:black">Tuesday, </span>
</b><b><span style="font-size:11.0pt">March 25<span style="color:black">, 202</span>5,<span style="color:black"> at 3:30pm</span></span></b><o:p></o:p></p>
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<p class="MsoNormal"><b><i><span style="font-size:14.0pt;font-family:"Aptos",sans-serif;color:#212121">Title:</span></i></b><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:#212121">
</span><span style="font-size:14.0pt;font-family:"Times New Roman",serif;color:#212121">Locality and parameter tradeoffs for quantum codes</span><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:#212121"><o:p></o:p></span></p>
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</span><b><i><span style="font-size:14.0pt;font-family:"Aptos",sans-serif;color:#212121">Abstract:</span></i></b><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:#212121">
</span><span style="font-size:14.0pt;font-family:"Times New Roman",serif;color:#212121">Quantum (error-correcting) codes protect from noise the delicate entanglement of quantum states that distinguishes quantum computers from classical computers. In practice,
local interactions — interactions between nearby qubits — are easier to implement than non-local ones, but constraining quantum codes to local interactions limits their quality. For example, the seminal Bravyi-Poulin-Terhal (BPT) bound states that a quantum
code with only local interations in two dimensions must satisfy kd^2<=O(n), where n,k,d are the number physical qubits, number of logical qubits, and distance of the code, respectively.<br>
<br>
In this talk, I will discuss how much "nonlocality" is needed to implement quantum codes beyond the BPT bound. Our works establish tight tradeoffs between the amount of nonlocality and the parameters of quantum codes, proving no-go results and showing matching
code constructions. This talk will not assume prior background in quantum computing.<br>
</span><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:#212121"><br>
</span><span style="font-size:14.0pt;font-family:"Times New Roman",serif;color:#212121">Based on joint works with Samuel Dai and Eugene Tang</span><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:#212121">.<br>
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</span><b><i><span style="font-size:14.0pt;font-family:"Times New Roman",serif;color:#212121">Bio:</span></i></b><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:#212121">
</span><span style="font-size:14.0pt;font-family:"Times New Roman",serif;color:#212121">Ray Li is an assistant professor at Santa Clara University. He received a PhD in computer science from Stanford University in 2022 and a BS in mathematical sciences from
Carnegie Mellon University in 2017. He was an NSF Postdoctoral Fellow at UC Berkeley from 2022 to 2023. His research interests include classical and quantum error correcting codes, fine grained algorithms and complexity, and combinatorics.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:14.0pt;font-family:"Times New Roman",serif"> <b><i><span style="color:black">Host:</span></i></b><span class="apple-converted-space"><span style="color:black"> </span><b>William Hoza</b></span></span><span class="apple-converted-space"><o:p></o:p></span></p>
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