I realized that Quantum Random Access Memory (qRAM) was proposed to make quantum computers more similar to classical one. Currently quantum computers have very constrained memory, given only quantum registers on quantum processors can be used for an algorithm to run. It is true that e.g. Qiskit language allows to use RAM or HDD of classical computer, however, resulting algorithms are hybrid quantum-classical.  I found some proposals how to implement qRAM, e.g. .  But my understanding is that the device is highly experimental nowadays.  So my questions are those:   Does anybody know about progress in this field? Some links to articles of state-of-art implementation of qRAM will be highly appreciated. What about IBM Q? Do we have an opportunity to use qRAM on IBM Q computer in foreseeable future (i.e. few years)?
Presently, how much information can a quantum computer store, in how many qubits? What restrictions are there and how does it vary across realizations (efficiency of data storage, ease of reading and writing, etc)?
As far as I know, ping needs to create a  (which needs either root access or cap_net_raw capabilities). From my understanding the trend these last years has been to remove  binaries and replaced them with . However when I look at the ping binary on my Fedora 32, it doesn't look to have any: $ ls -la $(which ping) -rwxr-xr-x. 1 root root 82960 May 18 10:26 /usr/bin/ping $ sudo getcap -v $(which ping) /usr/bin/ping $     Does ping need to open raw socket on fedora? Or is there another way to give it the permission to open a raw socket? Windows Unable to Delete ._. File I currently have a file on the root of my external hard drive simply named ._., which I am guessing was added to my hard drive after using it on my MacBook a while ago.  I'm trying to delete this file on my Windows 10 machine; however Windows keeps claiming the file cannot be found.    I also tried deleting the file through an elevated command prompt; however the same message is returned.    Is there any way I can delete this file from my hard drive through Windows? Get complete stats of process started/terminated during login of user account When I login, I notice many process quickly start and terminate in task manager. But it happens very fast and I cannot save details about them (like process name, command line, CPU usage,..)  How can I collect stats about them so I can view them later In , one learns two definitions of free groups associating with sets.        Let $A$ be a set, the free group of $A$, $F(A)$ is the initial object in the category $\mathcal{C}$, where \begin{equation} \operatorname{Obj}(\mathcal{C})=\{A\xrightarrow{g}G\}, \end{equation}where the codomain $G$ are groups, and \begin{equation} \operatorname{Hom}(\mathcal{C})=\{\text{Commutative Diagrams } A\xrightarrow{g_1}G_1\xrightarrow{\phi}G_2\xleftarrow{g_2}A\}  \end{equation} where $\phi$ are group homomorphisms.   Also $F(A)$ has the concrete construction with elements being non-redundant words with alphabet $A$, and the group multiplication being juxtaposition and reduction.      But what good are free groups? Why are they useful?  says they are useful in topology, but does not explain why explicity.   Can someone give some examples that an undergraduate can understand? I am asking about examples that can show the usefulness of this abstract construction. So I guess the identification of $\mathbb{Z}=F({a})$ does not really count. Proof that for $a,b,c\in \mathbb{R}$, hold that $\left |\sqrt {a^2+b^2}-\sqrt {a^2+c^2}  \right |\leq \left |b-c  \right |$. Give me a clue, I don't have any idea to work with that inequality. How to know if an object has an attribute in Python Is there a way in Python to determine if an object has some attribute?  For example:  &gt;&gt;&gt; a = SomeClass() &gt;&gt;&gt; a.someProperty = value &gt;&gt;&gt; a.property Traceback (most recent call last):   File "&lt;stdin&gt;", line 1, in &lt;module&gt; AttributeError: SomeClass instance has no attribute 'property'   How can you tell if a has the attribute property before using it? Is there any Android XML documentation? Without solving the equation, show that all nine roots of $(𝑧 − 1)^{10} = 𝑧^{10}$ lie on the line $Re (𝑧) = \frac{1}{2}$ Problem: Without solving the equation, show that all nine roots of $(𝑧 − 1)^{10} = 𝑧^{10}$ lie on the line $Re(𝑧) = \frac{1}{2}$. I would like to say I tried something but I am actually clueless. I was thinking maybe I could use De Moivre's theorem but I am not sure how. Any hint would be appreciated. Are there any published details of Kenobi's communication with Lars family on Tatooine before ANH? Are there any galois fields which consist of product of two primes, as in $\mathrm{GF}(2\cdot 3) = \mathrm{GF}(6)$? Adding holes simultaneously within mesh Im trying to add multiple holes within my mesh, so I divided it up, and then used cylinders shapes to make the holes. On the top image I used the Boolean operation. And on the bottom image, I subdivided one of the rectangles and used the looptool method with the circle. Once I add a subdivision modifier I am getting weird result with the Boolean but the operation holes, but the bottom Hole looks more acceptable once cleaned up. Is one or the other method the correct way? Disk full, du tells different. How to further investigate? I have a SCSI disk in a server (hardware Raid 1), 32G, ext3 filesytem. df tells me that the disk is 100% full. If I delete 1G this is correctly shown.  However, if I run a du -h -x / then du tells me that only 12G are used (I use -x because of some Samba mounts).  So my question is not about subtle differences between the du and df commands but about how I can find out what causes this huge difference?  I rebooted the machine for a fsck that went w/out errors. Should I run badblocks? lsof shows me no open deleted files, lost+found is empty and there is no obvious warn/err/fail statement in the messages file.  Feel free to ask for further details of the setup. Colors in Photoshop CS6/CC look different than in browser? One of my friends, a graphic designer told me recently that sometimes colors in Photshop look slightly different than the ones rendered in browser.  I know it is possible when you save a file and then use it on a website due to palettes, but he uses given color in PS, for example #b81e1e, then he creates a DOM element and sets its background to #b81e1e and the color is rendered differently in browser than in PS (I guess it's not that subtle as he can easily spot it). It's not a regular thing and it doesn't happen always, but he states it happened to him a few times, although he can't really tell me with witch colors.    Is it even possible? Because I have never really heard about anything like this &amp; nothing like this ever happened to me... Capturing SOAP requests to an ASP.NET ASMX web service Every metrizable space with a countable dense subset has a countable basis How strong of magnetic field would noticibly attract a person? There is iron in our blood, which is magnetic. Roughly how strong would a magnet have to be to induce a noticeable attraction? It would be nice to know this for several distances. Also, do electromagnets that strong exist? Drush CC all returning "No Drupal site found, only 'drush' cache was cleared" I've tried other solutions, but none of them are specific to my setup. I just started using the new Linux subsystem featured in the recent Windows 10 update. I'm using WAMP x64 v3.0.6, and have successfully cloned my website and got it up and running. At the root of the Linux subsystem, I installed Drush globally with Composer, using the directions given on the .  Typing drush status returns the following when I run it in my default directory:  Drupal version         :  7.50  Site URI               :  http://default  Database driver        :  mysql  Database hostname      :  localhost  Database port          :  Database username      :  root  Database name          :  aerosphere  PHP executable         :  /usr/bin/php  PHP configuration      :  /etc/php5/cli/php.ini  PHP OS                 :  Linux  Drush script           :  /home/bob/.composer/vendor/drush/drush/drush.php  Drush version          :  7.1.0  Drush temp directory   :  /tmp  Drush configuration    :  Drush alias files      :  Drupal root            :  /mnt/c/wamp64/www/drupal-7.50  Site path              :  sites/default   But, as mentioned in the title, drush cc all returns No Drupal site found, only 'drush' cache was cleared.[warning] I assume it has something to do with adding a path to the .bashrc, but I don't know what to add. Any tips would be greatly appreciated!  My question is different from "", they're on a Mac and using MAMP, and I'm using WAMP on Windows. I've tried the solutions offered on that post, but the issue has not been resolved.  I'm obviously having issues connecting to MySQL as I get this when I run mysql command:     The program 'mysql' can be found in the following packages: * mysql-client-core-5.5 * mariadb-client-core-5.5 * mysql-client-core-5.6 * percona-xtradb-cluster-client-5.5      Try: sudo apt-get install .   So I've added these lines to my .bashrc file:  PATH="$HOME/.composer/vendor/bin:$PATH" export PATH="/mnt/c/wamp64/mysql/mysql5.7.14/bin:$PATH"   The top line was added to get drush working. I've checked multiple times, and I have the path correctly set, but it's still not working. How can I install Sun/Oracle's proprietary Java JDK 6/7/8 or JRE? How do I summon the Golem? Why isn't an infinite direct product of copies of $\Bbb Z$ a free module?   Actually I was asked to show that it's not projective, but as $\Bbb{Z}$ is a PID, so it suffices to show it's not free.   I am stuck here. I saw some questions in SE, but there is no satisfactory answer at all.